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Ambrosia arteinisiifolia L. dominates abandoned fields after spring plowing in many parts of the eastern United States. Its seeds germinate at or near the soil surface in early spring, and the cotyledons become green shortly after they emerge. They are photosynthetically active, with a net photosynthesis dark respiration ratio (P/R) of 1.9. The primary leaves are photosynthetically more active than the cotyledons with a P/R ratio of 3. Photosynthesis of young A. artemisiifolia seedlings is 21 mg C02 dm-2 hr-1 at 1,076 X 102 lux, 250 C, and 300 ppm CO2. They approach light saturation at 1,076 X 102 lux (1.1 cal cm-2 min-) and exhibit appreciable photosynthesis at temperatures from 5? to 350 C. Their rate of photosynthesis increases with an increase of the ambient C02 concentrations comparable to that measured near the soil surface in the field. Although seedling photosynthesis is quite sensitive to decreasing water potential (*J.) between 0 and -10 bars, there is no further decrease between -10 and -20 bars. Furthermore, at this range of 'P photosynthesis is about 20% of that at 0 bars. In a plowed field these seedlings experience high light intensities, appreciable variation in daily temperature, high CO2 concentrations due to its flux from the soil, and low water potentials since the roots are in the upper part of the soil. Field-grown, mature A. artemisiifolia plants do not light-saturate even at 1,076 X 102 lux. Their photosynthetic rate at optimum light intensity, temperature, ala, and 300 ppm C02 is about 35 mg C02 dm-2 hr-1. This high rate of photosynthesis is accompanied by a high rate of transpiration (3 g H20 dm-2 hr-1). Photosynthesis in these plants is sensitive to temperature and reaches a peak at 200 C. The effect of CO2 enrichment on the rate of photosynthesis is not as pronounced in mature plants as in seedlings. Photosynthetic rates decline sharply between -10 and -15 bars BILL; however, appreciable rates are maintained even at '' of -20 bars for several hours. Photosynthetic recovery from water stress is rapid after watering and is attributed to the very low total plant resistance to water transport (1 X 106 sec cm-1). Mature plants have moderate photorespiration since their CO2 compensation point is reached at 50 ppm C02. These data indicate that A. artemisiifolia can not only efficiently exploit the environmental resources of the field during seedling and mature plant stages of its life cycle but also effectively function under the sometimes extreme conditions encountered in the field. These ecophysio- logical attributes coupled with complex germination behavior and genetic plasticity enable the species to be a successful pioneer in early successional ecosystems where the environment can be severe and unpredictable.

The relative abundance of the two crabs from Georgetown, South Carolina, compared to other areas characterizes Polyonyx as a more southernly distributed crab than Pinnixa. However, the zoeae and adults of Polyonyx are less tolerant of high temperatures than either the zoeae or adults of Pinnixa as indicated by both lethal limit and metabolic studies. Adult Polyonyx are also less tolerant of low temperatures than adult Pinnixa. Results indicate that Polyonyx is an obligate commensal of Chaetopterus, and Pinnixa is a facultative one.

The net CO2 exchange responses of Cladonia mitis, C. rangiferina, and C. uncialis from the Wisconsin Pine Barrens to irradiance, thallus temperature, and thallus relative water content were statistically compared for fall, spring, and summer. The absolute net photosynthetic rate of C. rangiferina exceeded that of C. uncialis under essentially all conditions and in all seasons; C. mitis's absolute net photosynthesis fluctuated with the seasons between these two contrasting species. Cladonia mitis showed significant intraspecific seasonal variation in net photosynthetic responses to temperature and irradiance. Cladonia rangiferina showed significant seasonal variation in dark respiratory response to temperature. Cladonia uncialis showed no significant intraspecific seasonal variation in net CO2 exchange responses. Significant interspecific differences in net CO2 exchange responses centered on the net photosynthetic responses to thallus temperature and relative water content.Despite its low net photosynthetic rates, C. uncialis is the most prevalent lichen in the Wisconsin Pine Barren ground-layer community. We attribute this not to broad physiological tolerance, but to its significantly slower drying rate. Lichens photosynthesize only when wetted. Cladonia uncialis photosynthesizes at generally lower rates than C. mitis or C. rangiferina, but it photosynthesizes longer under comparable environmental drying regimes. This and other aspects of the physiological ecology of the three species are discussed in relation to microdistribution and microhabitats within the Wisconsin Pine Barrens.

Photosynthesis and respiration of 4 species of the marine red algal genus Polysiphonia were evaluated under a variety of light, temperature and salinity conditions. The manometric results were compared with the local distribution and abundance of each species. The species can be separated into two distinct categories based on their overall distribution and temperature optima: (1) cold water plants [P. lanosa (L.) Tandy and P. elongata (Hudson) Sprengel], with peak photosynthesis at 21° to 24°C, but with active photosynthesis as low as 5°C; (2) plants with warm-water affinities [P. nigrescens (Hudson) Greville and P. subtilissima Montagne], having photosynthetic optima at 27° to 30°C, and exhibiting little or no photosynthesis below 10°C. The plants from the first group exhibit thermal injury at temperatures of 25°C and show a narrow tolerance to low salinities during periods of high temperatures. The plants from the second group show thermal injury at 30°C and have a wider tolerance to low salinities. The horizontal distribution of the 4 Polysiphonia species within the Great Bay Estuary System of New Hampshire, USA, is primarily governed by their tolerances to high temperatures and low salinities. The temperature optimum for each of the species corresponds to its particular estuarine distribution. Thus, P. subtilissima, having the highest temperature optimum, penetrated furthest into the Estuary, while P. lanosa, having the lowest temperature optimum, was restricted to the more coastal stations. There was a good correspondence between the natural distribution patterns and the manometric results.

1. Corispermum hyssopifolium L., a summer-annual member of the Chenopodiaceae, has a wide geographic range but is ecologically restricted. 2. In the Lake Michigan area it occurs primarily on five major phytophysiographic sites: eroding surfaces; depositing surfaces; stable surfaces, Ammophila breviligulata dominant; stable surfaces, Ammophila-Andropogon scoparius transition; and stable surfaces, Andropogon dominant. It is apparently not found on neighboring non-dune sites. 3. Considerable variation in density of bugseed was found among these sites, and individuals growing on them also showed considerable variation in vigor. 4. Largest individuals in the dunes were found to be associated with buried organic matter, presumably because of better nutrient supply. 5. Bugseed plants were found experimentally to grow very vigorously when supplied with a high level of nutrients in a "complete" solution applied in white quartz-sand culture. They are able to grow and survive as very small unbranched plants for over...

The physiological basis for the previously reported differences in the rate of respiration between high-shore-level and low-level populations ofPatella vulgatain the summertime has been investigated in relation to distribution differences between this species andP. aspera.The respiration rate of bothP. asperaand low-levelP. vulgatais low in the winter but increases in the spring to a level which is maintained until the post-spawning period in the autumn. The respiration rate of high-levelP. vulgatadoes not increase in the spring but remains at the low winter level. The inter-population difference in rate of respiration therefore appears in the spring and is maintained until the autumn.The difference in rate of respiration cannot be accounted for by differences in the amount of non-respiring tissue in equal weight individuals and is phenotypic and not genotypic, as indicated by transplantation experiments. These experiments also rule out the possibility of differences in age of equal weight individuals from the two populations being responsible.Respiration rate was found to be a function of both intertidal height and of the abundance of algal food in the habitat. It is suggested that the low-level population ofP. vulgatashould be regarded as the normal form and that the low respiration rate of high-level limpets in the summer represents a form of adaptation to the stresses of their habitat. It is possible that both nutritional level and temperature acclimation are important in this, and it is speculated that inability to reduce the level of metabolism may be one factor preventing the colonization of high-shore-level habitats byP. aspera.

Dans les années de forte pluviosité pendant la maturation du raisin, les attaques de Botrytis cinerea, sous forme de pourriture grise, apparaissent de plus en plus fréquentes et rapides. Il faut cependant souligner que la dernière décennie a été caractérisée par des années à pluviosité estivale anormalement élevée (1960, 1963, 1965, 1968, 1969).De nombreuses hypothèses, la plupart en relation avec les modifications des techniques culturales traditionnelles, ont été proposées pour expliquer l'ampleur nouvelle de ce phénomène. Cependant, dans un cru déterminé où les techniques culturales sont uniformes, on observe, suivant les parcelles, des différences très importantes dans les taux de pourriture et cela à une même date et pour un même cépage. Or, ces différences se retrouvent toujours d'une année à l'autre : on peut donc supposer qu'il existe des facteurs liés à la station et plus particulièrement à la nature du sol qui ajoutent leurs effets à ceux évoqués précédemment.

1. 1. The energy metabolism and comparative body water turnover rates of two species of kangaroo rats, Dipodomys merriami and Dipodomys microps , were measured in the natural environment over a 1-yr period with the D 2 18 O method. 2. 2. In addition to yielding energy metabolism data indicative of active, non-postabsorbtive animals, the results suggest that both species undergo diurnal torpor during periods of cold stress. 3. 3. Comparative water metabolism data indicate that D. merriami possesses a more conservative body water turnover rate than does D. microps . 4. 4. The D 2 18 O method of studying animal energy metabolism in the natural environment yields data not obtainable through conventional laboratory methods. It is preferable, therefore, that where practicable this method be employed in investigations of animal physiological ecology unless there is reasonable assurance that laboratory methods are adequate.

The haemocyanin in Callinectes sapidus Rathbun, a fully aquatic crab has been investigated in a population inhabiting a salt pond in a tropical mangrove swamp. Compared with the results of an earlier study on the haemocyanin perhaps on a subtropical population (Redfield, Coolidge & Hurd, 1926), the P 50 found here at 0 mm Hg CO 2 is remarkably low. It is suggested that this is in adaptation to low environmental oxygen concentrations resulting from, 1) high mean water temperature and salinity, and 2) the tendency of the animals to burrow into the sediment. High sensitivity to temperature and a relatively strong Bohr shift are demonstrated, and the possible physiological-ecological pressures involved are discussed. The responses to pH and temperature (Hill's n ) of the shapes of the equilibrium curves have also been investigated; the significance of these responses is still obscure. A possibly significant difference in Bohr shifts is noted with P CO 2 -dependent variation in pH, and with a naturally occurring variation among individual serum pH values.

Summary There are various forms within the species which exhibit a differential seasonal behaviour. These have been designated as ‘monsoon’, ‘winter’, ‘winter-summer’ and ‘summer’ forms. The life cycle of the ‘monsoon form’ starts under a high temperature regime and finishes under low temperature. The ‘winter’, ‘winter-summer’, and the ‘summer’ forms grow in constant low temperature, an initial low temperature terminating in a high temperature and in constantly-high temperature regimes respectively. The critical photoperiod for these forms ranges from 13 hours' duration to continuous light. The species does not grow at all in shaded localities. Many of the differentiating characters, however, become slightly less distinct when the different forms are raised together under a similar set of conditions in one or the other season, and this suggests that they originated from a common stock and evolved in response to environmental differences (as has been suggested for the various American species of Xanthium). The origin of the species with regard to its varying critical photoperiod has been discussed.

The genus Eriogonum Michx., a North American member of the Polygonaceae, has its greatest concentration of species in the drier parts of the western United States and northern Mexico. The species offer a dramatic example of adaptive radiation in the diverse growth forms they assume and the varied habitats they occupy. In California alone there are over 75 species, both annuals and perennials, which occur from coastal bluffs to alpine tundra and in the most severe deserts. On the Santa Monica Mountains of southern California, there are seven closely related species of Eriogonum all of which belong to the subgenus, Oregonium (Munz & Keek 1959). This mountain range offers a variety of habitats with different climates where adaptive radiation is apparent in Eriogonum, although on a smaller scale than that which is evident in the genus as a whole. Some of the species occupy very limited habitats; others are seemingly habitat indifferent. Torrey and Gray monographed the genus Eriogonum in 1870. Then, in 1936, Susan Stokes published a revision emphasizing geographical distribution and probable paleohistory of the group. She divided the genus into four subgenera corresponding to the four main geographical areas of distribution of the genus during the postglacial era. Stebbins

Weight-specific respiratory rates in males of 3 gammarids from different salinity regimes, ranging from the marine environment to strictly fresh water, were measured by routine manometric methods in order to assess the main as well as the interaction effects of salinity and temperature. The results were submitted to an analysis of variance. All species demonstrate a reversible more or less decreasing QO2 at increasing salinity. This statistically well established phenomenon does not depend on the salinity boundaries of the various species in nature. Salinity sensitivity increase at higher temperatures. The influence of temperature is great, with exception of the intertidal Chaetogammarus marinus, between 5° and 15° C. The effect of interaction of salinity and temperature on respiration was significant, again with the exception of Chaetogammarus marinus. The absence of the temperature effect as well as the interaction of temperature in salinity-dependent respiration have positive ecological implications in the fluctuating temperature regime of the intertidal area and probably are characteristic for this biotope.

MacKinney, G. 1941. Absorption of light by chlorophyllll solutions. J. Biol. Chem. 140:315-322. Mayr, H. 1909. Waldbau auf naturgesetzlicher Grunidlage. Paul Parey, Berlin. 568 p. McGregor, W. H. D., R. M. Allen, and P. J. Kramer. 1961. The effects of photoperiod on growth, photosy nthesis, and respiration of loblolly pine seedlings from two geographic sources. Forest Sci. 7:342-348. Mergen, F. 1963. Ecotypic variation in Pinuis strobuts L. Ecology 44:716-727. Milner, H. W., W. M. Hiesey, and M. A. Nobs. 1959. Physiology of climatic races. Carnegie Institution of Washington Year Book 58:346-450. . 1960. Physiology of climatic races. Carnegie Institution of Washington Year Book 59:313-318. Mooney, H. A., and W. D. Billings. 1961. Comparative physiological ecology of arctic and alpine populationis of Oxyria digyna. Ecol. Monographs 31:1-29. Scholander, Susan I., and Joan T. Kanwisher. 1959. Latitudinal effect oni respiration in some northern plants. Plant Physiol. 34:574-576.

The haemocyanins of five crabs ranging in habit from aquatic to terrestrial have been investigated. The mean P50 values of the respiratory pigments were determined at 0 mm Hg CO2 and 28 °C (the average environmental temperature of all the species). Comparison of these data adjusted to the individual mean physiological pH indicate an increase in P50 with terrestrialization, perhaps related to the greater abundance of oxygen in the aerial than in some the aquatic habits, and the progressive elaboration of lung breathing with terrestrialization. The Bohr shifts ( Δ log P 50 ΔpH ) were determined (using different PCO2 values to vary pH) and were found to decrease with terrestrialization, perhaps in adaptation to an associated rise in internal PCO2 (6–8-fold between the aquatic Callinectes sapidus Rathbun and the terrestrial Cardisoma guanhumi Latreille and probably resulting from progressive gill reduction. The temperature shifts (ΔH cal/mol) of the haemoeyanins were found and it is suggested that they diminish with increasing evironmental temperature and temperature fluctuation accompanying terrestrialization.

1. 1. Gravimetric and isotopic determinations of the respiratory and water metabolism of Perognathus formosus in the laboratory are in substantial agreement with values which are known from other heteromyid species obtained under similar conditions. 2. 2. Isotopic determinations in the field of these parameters in P. formosus yield respiratory metabolic values reflective of an active animal in a non-post-absorptive state. Body water turnover rates range from 2·4 to 4·0 times greater than those previously measured in heteromyid rodents. 3. 3. With the ability to measure metabolism in natural environments, continued reliance upon values obtained from laboratory experiments would seem limiting when insights into the physiological ecology of a species are sought.

An ecological comparison was made between an alpine population of Thalictrum alpinum L. from the White Mountains of California and diploid and triploid plants of an arctic population from Ogotoruk Creek, Alaska. In a uniform environment plants of the alpine population were found to differ physiologically from the arctic plants in their photoperiod requirement, temperature of optimum photosynthesis, and photosynthetic light efficiency. Arctic triploid differed from diploid plants primarily in their greater vigor and photosynthetic capacity. Certain of the physiological differences between populations correlate with structural leaf characteristics, and are comparable to those previously found between arctic—alpine populations of Oxyria digyna. The ecological differences between the arctic chromosome races are discussed in relation to polyploid frequency in the arctic. See full-text article at JSTOR

Seeds of the winter annual Viola rafinesquii Greene exhibit true dormancy at the time of maturity and dispersal in mid to late spring. During the summer rest period the seeds pass from a state of true dormancy to one of relative dormancy and finally to what may be called a state of complete nondormancy. As the seeds enter relative dormancy they will germinate mostly at relatively low temperatures (10, 15, 15/6, and 20/10 C), but as after-ripening continues they gain the ability also to germinate at higher temperatures (20, 25, and 30/15 C). During June, July, and August seeds will not germinate at field temperatures even if kept continuously moist. But by September and October seeds may germinate to high percentages over a wide range of temperatures, including September and October field temperatures. This pattern of germination responses, involving breaking of true dormancy and widening of the temperature range for germination during relative dormancy, appears to be an adaptation of the species to a hot, -dry season. Seeds of V. rafinesquii stored on continuously wet soil (field capacity) or on soil that was alternately wet and dried during the summer did not after-ripen at low temperatures (10, 15, 15/6, and 20/10 C) but did after-ripen fully at high temperatures (20, 25, 30/15, and 35/20 C). Thus, the high temperatures that V. rafinesquii "avoids" by passing the summer in the dormant seed stage actually are required to break seed dormancy and, therefore, are essential for completion of its life cycle.

1. This study tests the hypothesis that physical factors limit the ranges of five species of limpets (Acmaea) inhabiting the splash zone (Zone I) and upper midtidal (Zone II) of the Central California rocky shore. Two criteria are considered necessary to establish the hypothesis. First, interspecific differences in adaptation to physical factors must permit exploitation of different portions of the intertidal gradient. Secondly, physical conditions, by occasionally causing mortality, must set the limits of ranges at different levels depending upon the interspecific differences in physiological tolerances.2. Dilution by winter rainwater runoff probably presents no osmotic threat to Acmaea. No pronounced differences are evident in either resistance to or tolerance of dilution. All five species tolerate immersion in fresh water for periods in excess of the maximum exposure expected in nature. Under exceptional circumstances some Zone I limpets may experience entrapment and lethal dilution in fresh water seep...

The lichen Cladonia mitis (Sand.) from the Wisconsin Pine Barrens showed no significant differences in the light—dependence of net photosynthesis of sun— and shade—grown mats. Maximal net photosynthesis was 1.13 mg CO_2. g(—1) (air dry weight). hr(—1) at 3.88 x 105 ergs. cm(—2). sec(—1), 22.5 plus or minus 1.0 degrees,and near optimal thallus water content; the light compensation point was 0.36 x 105 ergs. cm2. sec(—1). After dormancy was broken by wetting the sun— and shade—grown C. mitis mats had comparable initial dark respiration rates of —0.47 and —0.48 mg CO2. g(—1). hr(—1), respectively, at high thallus relative water content (ca. 90% RWC). After drying to thallus RWC in the range 62—72%, the dark respiratory rates of the sun—and shade—grown C. mitis, respectively —0.33 and —0.25 mg CO_2. g(—1). hr(—1), differ significantly. The decreases in thallus RWC over 196 plus or minus 3.7 minutes of 37% and 29% for the sun— and shade—grown C. mitis, respectively, also differed significantly. The average annual growth rate of 5.2 plus or minus 0.2 mm. yr(—1) was the same for both sun— and shade—grown C. mitis. These characteristics of sun— and shade—grown C. mitis may be an important aspect of the physiological ecology of the plants.

Summary Digera alternifolia Aschers, is one of the common weeds of crop fields. It is observed that this weed is associated with certain crops only and remain absent from the fields of the other crops. So also, it fails to form association with other commonly invading weeds of the area. A possible cause of this selective association was sought. It appears that the root exudates of the crops play important role in such a distribution and association. The role of the inhibiting substances present in this weed becomes important as it can hamper the germination of the seeds of the other common weeds. We can conclude therefore that the association of plants may depend upon the substances produced in plant body and their retainment in side the body or release in the environment.

Field observations were made on the ecological life cycle of the winter annual Arabidopsis thaliana (L.) Heyn. from a population in central Tennessee, and a detailed laboratory study was conducted on the physiological responses of the seeds to temperature in light (14-h photoperiod) and constant darkness. At maturity and dispersal (late April and early May), seeds germinated to high percentages only at low temperatures (5–10 °C) in light. With storage from May to September and October (1) the maximum temperature for germination in light increased from 15 to 30 °C and in darkness from 10 to 20 °C and (2) the optimum temperature for germination in light increased from 5 to 15–20 °C and in darkness from 5 to 5–10 °C. During the spring–summer period seeds were dormant at temperatures simulating those in the natural habitat. In September and October, seeds in light germinated to high percentages at simulated September and October temperatures but did not germinate in darkness at the September temperatures and germinated poorly at October temperatures. Regulation of germination so that it occurs in early autumn allows A. thaliana to persist in a summer-arid habitat.

Summary: The distribution and physiology of Cyanidium caldarium in its natural habitat in acidic hot springs and hot soils have been studied. This eucaryotic alga was the sole photosynthetic organism in habitats with pH less than 5 and temperatures greater than 40°. The upper temperature limit of the alga was 55° to 56° and the optimum temperature for growth was 45°. Temperature strains such as are found in blue-green algae of alkaline thermal habitats were not found for Cyanidium caldarium. In aquatic habitats the lower temperature limit was about 35° to 36°, the organism apparently being unable to compete at temperatures below this with other algae. In soils the alga was found at temperatures as low as 10°, apparently because in terrestrial habitats competition with other algae was less significant. The pH range at which the alga has been found in nature was from 0·05 to 5·0 and growth in culture occurred over this whole range. The optimum pH for growth was between 2 and 3. In nature the alga was found in habitats of widely varying light intensity, up to 7000 ft-candles. The alga became adapted to reduced light intensity by increasing its photopigment concentrations. Photosynthesis in populations adapted to reduced light intensities was inhibited by high light intensities. The alga grew well on glucose in the dark, and the concentration of photosynthetic pigments was reduced. When such bleached cells were transferred to the light in the presence of glucose, pigments were not synthesized and heterotrophic growth continued; when glucose was omitted, pigment synthesis occurred and photosynthetic growth resumed. Glucose did not inhibit pigment synthesis when added to cells growing in the light.

Summary Cuticular waxes of one and two year old Pinus silvestris needles, monthly analyzed by gas liquid chromatography, show pronounced differences in accordance with season and needle-age. In the hydrocarbon fraction the low-molecular components decrease from late summer to next spring. At the end of July there is a deep minimum. The relative amount of the most important alcohols and esters also varies with season and needle-age. In some cases these differences run up to 30 % of the total fraction. Finally these findings are discussed in relation to their effect for chemotaxonomy, ecophysiology and pathology.

1. Tortula ruraliformis is a xerophyte whose structura1 and physiological features suit it to an environment subject to cosiderable desiccation and sand movement2. Untwisting and expansion of the leaves depend on hygroscopic movements but turgor phenomena may also be concerned.3. The moss is poikilobydrous, its water content quickly equilibrating with the environment. The leaves unfold at relative humidities pater than 90 %.4. The tops of the shoots are physiologically the most active. Analyses of the chief constituents (carbohydrates, nitrogen compounds. ash) have been made.5. Sucrose is the most important photosynthetic product, making up usually S % or more of the dry weight of the plant. Starch is absent from the leaves, and most of the hexose is glucose.6. Photosynthesis virtually ceases when the leaves are tightly rolled inwards round the stem.7. On re-hydration of moderately drougbted shoots, the respiration rate rises quickly from a very low value, and the tissues can photosynthesize immed...

It has long been known that the rate of transpiration from the leaves of different species of plants is not the same, even if the plants are growing under identical environmental conditions. Obviously such variations in the rate of transpirational water loss must be due to conditions and factors which are internal in the leaf. The relative resistance of the leaves of a species to water-vapor loss may be an important factor in determining the water relations of that plant, i.e., whether it is a mesophyte, a hydrophyte, or a xerophyte. It has been assumed that a plant the leaves of which were relatively resistant to water-vapor loss was better fitted to withstand conditions of diminished water supply than one with leaves not so resistant. It is doubtful whether the ability of a plant to conserve water in its leaves under conditions adverse to the maintenance of a favorable water balance may be accepted as a universal criterion of relative xerophytism, but this is probably a factor. A simple, rapid, and reasonably accurate method for measuring the rate of water-vapor loss from leaves, especially if it be adapted to field use, is a necessity in many studies of physiological ecology. The cobalt chlorid paper method first devised by Stahl (7), and considerably improved by later workers, has been developed upon a quantitative principle which appears to give satisfactory results in field measurements of the rate of water-vapor loss from leaves. The general principle of this method is well known. Absorbent paper, such as filter paper, is soaked in a dilute solution of cobalt chlorid and dried. When dry this paper is blue in color, but upon exposure to moist air the cobalt chlorid rapidly takes up water vapor and becomes hydrated. This hydration is accompanied by a change in the color of the paper from blue to a pale pink. If a small piece of this cobalt chlorid paper is applied to a leaf surface, and protected from atmospheric moisture by glass or some other transparent substance, the time required for the paper to change from blue to pink is a measure of the rate at which that leaf surface is losing water vapor to the paper. Livingston and his associates (3, 4) introduced a number of improvements in this method of determining the rate of water-vapor loss from leaves. For the details of their methods the original papers should be consulted. A standard evaporating surface was used by these workers as a basis for comparative measurements. A free water surface was first used as a standard

All the freshly collected mature seeds of M. pudica were greenish in colour, whereas 7 year old stored seeds were a mixture of greenish and brownish seeds. The greenish seeds had hard seed coat and acid treated as well as sand rubbing for 6-10 min greatly enhanced their germination percentage. The brownish seeds were simply the deteriorated form of greenish seeds. Leaves and pods had higher contribution to total plant dry weight in ungrazed field and in pot-cultured plants clipped a month before flowering. The young shoots of the plant had 18.9% crude protein, 0.46% phosphorus and 25.4% crude fibre on dry weight basis.Key words: Hard seed coat, Mimosa pudica, scarification, dry matter productionDOI: 10.3126/on.v7i1.2568Our Nature (2009) 7:177-181

The metabolic or respiratory rate, measured as the aerobic oxygen uptake, of the limpets Patella vulgata L. and P. aspera Lamarck was determined over a range of temperatures in January and in July. In order to determine the effects upon metabolism of adaptation to habitat, P. vulgata living at high shore levels were compared with those living at low shore levels.The respiratory rate is proportional to the power –0·3042 of the fresh body weight and the relationship is not affected by temperature or season, and is the same for both species.There is very little difference in the rates of respiration of equal weight individuals of P. aspera and either group of P. vulgata in January. In July the respiratory rate of low-level P. vulgata and of P. aspera is higher than in January whilst that of the high-level P. vulgata is little changed.The Q10 of respiration had a low value between the temperatures of 15–20° C in both species, and this is thought to represent a hitherto unrecognized form of acclimation to maintain metabolic constancy over the mean environmental temperature range. In P. vulgata low values of Q10 were correlated with high environmental temperatures. Lower Q10's were recorded in July than in January and, in addition, limpets which were adapted to the elevated temperature of high shore levels in July had lower Q10's than the limpets from low shore levels. This apparent acclimation of Q10 was not observed in P. aspera.The significance of the differences in metabolic rate and in Q10 are discussed in relation to acclimation and its importance in the ecological distribution of the two species.

1. Seasonal water metabolism in the herbivorous desert lizardSauromalus obesus (chuckwalla) was measured with tritiated water (HTO). Electrolyte budgets were obtained from field and laboratory measurements. These data describe the roles of various excretory organs in maintaining balance and permit evaluation of some aspects of the physiological ecology of these lizards. 2. When vegetation was succulent, chuckwallas obtained more than enough water from their food to meet their needs (Table 5). The excess was excreted rather than being stored (Table 1). 3. Although water requirements of chuckwallas maintaining constant weights are low in comparison to some other desert vertebrates, metabolic water production is insufficient to balance losses. These lizards must eat succulent vegetation to maintain water balance. 4. When vegetation was dry (summer), chuckwallas remained in crevices most of the day and did not eat. This behavior resulted in a considerable reduction in water loss. 5. These lizards did not drink rain water. 6. During drought, chuckwallas became dehydrated (Fig. 2), but fractional fluid volumes were maintained at normal levels (Table 1), as were plasma electrolyte concentrations (Table 2). 7. Chuckwallas entered winter dens in October weighing only two-thirds as much as in April (Fig. 1). They did not grow in length during 1970. 8. The diet was always hyperosmotic with K+ predominating, but this load was excreted by the nasal salt glands and as precipitated potassium urate (Table 7). These avenues of electrolyte loss require little water (Table 6), resulting in effective separation of water excretion from electrolyte excretion.