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Functional and numerical responses of the predators:Phytoseiulus persimilis Athias-Henriot,Metaseiulus occidentalis (Nesbitt), andAmblyseius chilenensis (Dosse) [Acarina, Phytoseiidae] were observed at prey (Tetranychus urticae Koch [Acarina, Tetranychidae]) densities up to 300 prey/6.45 cm2. Neither functional nor numerical response curves revealed any prey-predator interference effects, i.e.: the dome-shaped response curves (Holling, 1961), did not occur.

NUMEROUS STUDIES have been made on the respiration of land plants and some on water plants, but very few such studies have been made on semi-submerged water plants (Samantarai, 1938). Yet, from the standpoint of the environment, semi-submerged plants offer very interesting material because of the belief that they were once terrestrial and have subsequently invaded the water, and because it is difficult to understand how the rhizomes of plants with terrestrial form are able to endure the condition of low aeration that exists in the mud at the bottom of a pond (Cole, 1932).2 That this ability is not due to particular structural features may be deduced from the fact that rhizomes of very diverse structures are found imbedded in the submerged mud. For example, Furthermore, the ability to endure the nearly anaerobic conditions of the submerged mud is not associated with a particular habit of growth and fruiting, because all of the species of thick spongy rhizomes mentioned above as well as one of the toughest and firmest of rhizomes to be found anywhere, namely, that of Scirpus validus, grow progressively through the mud, branching only occasionally, sending up fruiting culms at irregular intervals, and always dying and becoming decayed at the rear; while the hard young rhizomes of Typha latifolia and Sparganiurn eurycarpum and the corms of Sagittaria latifolia are formed one at the terminal end of each of the slender spongy stolons that radiate from a parent plant which dies at the end of its fruiting season.

The centrifuge has been used in the study of the constitution of solutions by a number of investigators. Des Coudres and Tolman* used it with electrolytes to measure the initial tendency towards sedimentation without, however, prolonging the experiment sufficiently to allow the sedimentation to take place, but measuring the e. m. f. instantaneously set up in a centrifugal as in a gravitational field. Work on ordinary electrolytes has been in abeyance for twenty years. To Svedberg is due the remarkable achievement of realising centrifuges of high power in which the process and attainment of sedimentation may be observed by optical methods throughout the operation of the centrifuge. This introduces a new and invaluable quantitative instrument of singular power for the examination of innumerable problems in colloid and chemical science.

The biology of Paracheyletia bakeri (Ehara) and its effectiveness as a predator of Tetranychus urticae Koch was studied in the laboratory. P. bakeri took an average of 47 days to mature at 22°C. After this prolonged developmental period, each female laid an average of 0.7 eggs per day during an ovipositional period of 36 days. From the life history data, the intrinsic rate of increase was determined to be 0.05 females produced per female per day. During a generation time of 55 days the net reproductive rate for P. bakeri was 15.6 at 22°C. Prey consumption ranged from 0.9 male T. urticae per day for a larva of P. bakeri to 1.6 males per day for an adult female. During population interactions of P. bakeri and T. urticae, this predator was unable to reduce a high population of T. urticae or maintain a population of T. urticae at a low density.

The life history ofAmblyseius chilenensis was studied in a laboratory at 16.4, 25 and 32 °C. The rates of development, prey consumption and oviposition varied directly with temperature. From the life history data the intrinsic rates of increase were determined to be 0.112, 0.287 and 0.307 at 16.4, 25 and 32° respectively. The net reproductive rates were 12.73, 29.09, 17.82 and the mean generation times were 22.72, 11.74 and 9.38 days at 16.4, 25 and 32° respectively.

1. Semi-submerged water plants inhabit their particular habitats very largely on the basis of adaptation in respect to their oxygen requirements for respiration and growth. The oxygen requirements for growth are different for different species. 2. The percentage of oxygen found to be most conducive to the growth of young shoots in certain of the species studied was, respectively, Nuphar advenum 0 to 1, Peltandra virginica 0 to 1.5, Pontederia cordata 0 to 10, Typha latifolia 4.6, Acorus calamus 10, Scirpus validus 10. Buds of all these species were able to endure prolonged exposure to pure nitrogen, but no growth occurred in A. calamus, S. validus, and T. latifolia in nitrogen. Shoots of S. validus previously formed were killed in nitrogen. 3. The excellent growth of N. advenum in nitrogen was not affected by either the presence or absence of oxygen in the internal atmosphere of the rhizome so long as the apex was surrounded by nitrogen. When the apex was surrounded by air, no growth occurred even though ...

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(1847). Saxon Tower of Trinity Church, Colchester. Journal of the British Archaeological Association: Vol. 3, No. 1, pp. 19-22.

Populations of T. pacificus McGregor were followed on individual vines throughout the 1971 season in 2 vineyards in the San Joaquin Valley to determine the effects of the mites on quality and quantity of Thompson seedless grapes. The Pacific mite densities ranged from an average of 2.1 to 225 mites per leaf per week for the 3 weeks of heaviest infestation in one vineyard, while mite densities ranged from an average of 10.8 to 205.8 mites per leaf per week for the 4 weeks of heaviest infestation in the other vineyard. The yield and percent sugar content of the grapes was taken at harvest time. Vine-by-vine analysis of mite densities times yield showed no correlations between the number of mites per leaf and the weight or sugar content of the grapes for the densities of mites encountered under the conditions of this experiment.

The inheritance of yield components was studied in a cross of two varieties of cowpea (Vigna unguiculata), and the relationships among the components and yield were examined in the F2 of a cross and in a trial of 22 varieties. The main objective was to determine the suitability of using the components as selection criteria for increasing seed yield. All the components appeared to be under polygenic control and transgressive segregation in the F2 was observed for pod length and number of seeds per pod. Narrow sense heritability estimates ranged from 19.8% for number of pods per plant to 60.3% for pod length. Most of the genotypic correlations between pairs of yield components were significant. Correlation of yield per plant was negative with pod length, but positive with the other components. Number of pods per plant was consistently correlated with yield. However because of low heritability for number of pods per plant, this component may only be used as a preliminary selection criterion while the final selection is based on yield itself.

The life history of M. occidentalis (Nesbitt) (Acarina: Phytoseiidae) was determined at a diurnal temperature range of 15–°C. The rates of predation for all stages of M. occidentalis on the eggs of the two-spotted spider mite, Tetranychus urticae Koch, also were observed at this cyclical temperature. From the life-history data, a life table was constructed for M. occidentalis . The intrinsic rate of increase was found to be 0.183 individuals per female per day, and the population multiplied 24.29 times in a generation time of 17.43 days.

Disturbed linkage. I. Partial manifestation and differential viability at the same locus in backcross data

A reinforced-concrete dual-purpose underground parking garage and personnel shelter designed for a long-duration incident pressure of 40 psi was tested. The shelter was exposed to shot Priscilla, an approx. 37-kt 700-ft balloon burst (June 24, 1957), at a ground range of 1600 ft (predicted 35-psi peak incident-pressure level). The recorded peak incident pressure at the shelter was approximately 39 psi. Postshot soil borings were made to obtain undisturbed samples for determining soil characteristics. Preshot and postshot field surveys were made to determine the total lateral and vertical displacement of the structure. The test structure provided adequate protection from the effects of the test device at the test GZ distance. Despite failure of the door sealing gasket, a rise in pressure in the interior did not exceed 1.0 psi. The flat-slab roof and supporting structure were more than adequate to resist the 39-psi peak incident test loading.

Over 50 people attended this seminar, organised by the Department of Natural Sciences of U.N.E.S.C.O., including 32 specialists from 22 African university institutions. Documents had previously been submitted by each participating country, summarising the following data on science faculties: numbers of lecturers and students, capacity of departments, facilities for teaching and research, and development plans. The working languages were English and French; simultaneous interpretation was provided. The seminar was conducted mainly in plenary sessions; papers written mostly by U.N.E.S.C.O. consultants served as bases for discussing the teaching of specific subjects (mathematics, physics, geology, chemistry, and biology), the emphasis throughout being on first-year university work. More general topics included co-operation between university and government, and between African countries in science teaching.

In order to measure the contraceptive experience of the respondents following acceptance of family planning a National Acceptor survey (NAS) was carried out among a national probability sample of women who had been registered as new acceptors in Philippines family planning clinics during 1970. The survey was conducted in January-March 1972 by the Family Planning Evaluation Office of the University of the Philippines Population Institute. This paper summarizes the major findings of the survey. The interviews conducted on a sample of 1865 women who accepted family planning at the clinics in Philippines showed that: 1) after 1 year about 30% of the acceptors stopped practicing contraception; and 2) 22% became pregnant. 7 variables were measured: desire for additional children educational attainment religious affiliation place of residence distance from the clinic cost of supplies and husbands behavior. Only the contraceptive method first accepted had a strong effect on the likehood of continuation of contraception or pregnancy. The IUD proved to have the highest continuation rate and the lowest pregnancy rate of all methods.

TEN years ago we found that two portions of the same solution of soap could be brought into the states of either sol or typically transparent jelly respectively at the same temperature, and that such significant properties as conductivity, lowering of vapour pressure, concentration of sodium ion as measured with the sodium amalgam electrode, etc., were identical in both these states. Sol and jelly differed only in mechanical properties such as rigidity and elasticity. We therefore drew the obvious conclusion that the rigid structure of the jelly must be built up by progressive linkings together of the particles which pre-existed in the sol (Trans. Ghem. Soc, London, 117, 1506; 1920).