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Seventeen species of Coleoptera, Lepidoptera, Diptera, and Hymenoptera showed chemical differences by the method of paper chromatography in an evaluation of the method for taxonomic purposes. The analyses were complicated by pattern differences evident in larval, pupal, and adult stages of some species. Geographic isolates of Malacosoma disstriaHbn. as well as of Chamaepsila rosae(F.) and physiological entities within Pristiphora erichsonii(Htg.) show identical patterns; however, differences are found at specific levels. Paper chromatography is therefore a valuable taxonomic tool, especially as the technique is capable of considerable refinement.

A new ultramicromethod for the quantitative estimation of amino acids by paper partition chromatography is described. The material required and the procedure adopted are detailed. As an application of this new method, a quantitative estimation of the free amino acids present in the blood of the last larval instar of Galleria mellonella(L.) is presented. The results obtained, when converted into total amino nitrogen, compare favorably with total amino nitrogen results already published in the literature.

The protein constituents of the larval diets of queen and worker honeybees were separated by continuous paper electrophoresis. The electrophoretic patterns of royal jelly of any age and the early worker diet were similar and comprised five ninhydrin-reactive bands or fractions. Fraction 1 (nearest the cathode) contained lysine as a free amino acid. Fractions 3 and 4 appeared to be complex polypeptides. Alanine, asparagine, aspartic acid, glutamic acid, glycine, histidine, isoleucine and/or leucine, lysine, phenylalanine, threonine, tyrosine, valine, and an unidentified substance were found in chromatograms of the acid hydrolyzate of fraction 3; the hydrolyzate of fraction 4 contained the same amino acids except for threonine. Fractions 2 and 5 were not characterized. Electrophoresis of the diet of worker larvae older than 3 days showed a pronounced fading of all bands, attributable to the dilution of the solids by the addition of honey which occurs at this time. There appeared to be no qualitative differences between the protein fractions of royal jelly and worker diet which would account for the differentiation of female honeybees into queens and workers. The decrease with age in the percentage of protein in the worker diet may be significant.

The size at which crustaceans become mature can be a useful gauge in the study of environmental effects on field populations. The use of probability paper in rigorously defining the mean size at onset of sexual maturity avoids some of the confusion inherent in other methods of assessing size at maturity and permits an objective comparison of differences between discrete populations. Both logical and mathematical considerations in the use of probability paper for analyzing field data have been treated; and some sample data reveal how one might detect environmental effects on population structure. In this case the data indicated that mole crabs (Emerita analoga) may have grown at different rates in proximate populations.

A qualitative and semiquantitative analysis of the free amino acids in the hemolymph of nine insect species was carried out with the method of paper partition chromatography. Details concerning the above method as applied to insect blood analysis are given. A discussion of the results obtained with those published in the literature is included. From 16 to 24 free amino compounds are regularly identified in insect blood, many of them in high concentration. There are qualitative and quantitative differences in amino acids between different insect species. Quantitative analyses of the free amino nitrogen of insect hemolymph are presented at the end of the paper. These quantitative determinations were carried out by means of the Van Slyke gasometric apparatus using the nitrous acid reaction.

Previous papers dealing with behaviors and activities of blood cell nuclei have been recording mainly results with the imprint method and observations of blood cells cultured in vitro. The present paper demonstrates that the Feulgen "gentle squash" method as well as digestion with NHCl followed by toluidine blue staining at pH 4 reveals the same nuclear behaviors as the imprint method. Imprinting on millipore filters with subsequent fixation in Zenker's acetic solution followed by the Feulgen or toluidine blue staining method (the latter with or without previous NHCl digestion) is reported for the first time. The millipore imprint preserves a thicker layer of cells than imprinting on glass slides. Also cell stages which may not easily stick to glass seem to adhere well to the millipore filter. The filter imprint may in places present as many cell layers as a thin slice cut on the microtome, but without the disadvantage of having large or elongated cell stages cut into pieces by the microtome knife.

The paper describes two species of Haemobaphes(Copepoda: Lernaeoceridae) found on fishes in the waters of British Columbia. The species are: H. dicerausWilson, 1917 and H. intermediussp.nov., whose adult, modified females have been found in Georgia Strait. In addition, lernaeocerid larvae of the genus Haemobapheshave been found and several developmental stages are described. The paper also discusses the present status of the genus Haemobaphesand speculates on the possible life cycles of the two species described.

Fully fed larvae and pupae of the three castea of honey bee were reared in various artificial cells in the laboratory. The effects of humidity, removal of cell parts, orientation of brood in various positions, and use of different artificial cappings on brood development were tested.Rearing was successful in wax cavities covered with cellophane and is gelatin capsules with one end covered with paper tissue. Bees emerged quickly and easily through paper tissue with minimum loss of weight when they were physically ready to do so. Labial gland secretion was probably used to moisten cappings during emergence. Cell size was only critical for drone brood. Relative humidities of 40–80% gave good results. Ecdyses were more successful when the anal ends touched side or end walls of the cells. The placement of prepupae or pupae in various abnormal positions had little or no effect on subsequent development.

In Part I of this paper consideration was given to the role of climate in the initiation of outbreaks of the spruce budworm in New Brunswick. Analysis of the available weather data showed that the 1912 and 1949 outbreaks developed after several consecutive dry summers. Support was given to the theory of climatic release, which explains the time and place of outbreaks on a climatic basis. However, the recorded history of the spruce budworm also shows that high populations appeared in New Brunswick shortly after "spreading" through Quebec, and this suggests that the New Brunswick outbreaks are also a continuation of this spread. In the present part of the paper consideration is given to the role of dispersal. Moth dispersal is a more effective agent of spread than larval dispersal. Moths may be transported by convectional and turbulent air currents for long distances. Light traps used to detect the incidence of moth movements, showed that large segments of a population may be transferred from one area to another. Unspent females often predominate in these movements. Moth invasion was not detected before the 1949 outbreak although there is evidence from other sources that it occurred in 1948. When deposited in dense, mature, softwood stands, the moths can create outbreaks, but when deposited in young, open, or mixed-wood stands the ensuing high populations soon decline unless bolstered by repeated invasions. Populations in New Brunswick showed gradual and general increases as early as 1947. It is thought probable that these increases resulted from the build-up of local populations through climatic release. The nearest highly-populated centers were over 100 miles to the west in 1947. Later, invasion of moths from centers outside of the Province may have hastened the process.

Two species of starlings (Sturnidae) have established themselves in southwestern British Columbia: the crested myna (Sturnus cristatellus), by escape from captivity about 5897, and the common starling (Sturnus vulgaris), by natural invasion during the 1950's. The crested myna has shown little capacity to expand its range or its population. The common starling is in an active phase of increasing density and distribution. These sympatric populations have been studied over a period of 3 years. This paper reports comparative aspects of reproduction, and resource use by the two species.We have found that the nesting season for starlings was synchronized into definite peaks of nest building, egg laying, hatching and fledging, which was not the case for crested mynas.Clutch and brood sizes were higher in starlings than mynas. Starlings successfully reared more second broods than mynas (38% vs. 9%). Per 100 pairs/annum, starlings contributed significantly more offspring (547 compared to 238) to the sturnid population.Although development of plumage and endothermy were similar in myna and starling chicks, feeding rates, quality of foods, and subsequent growth rates of chicks were significantly different.Egg transplant and heater nest box experiments suggested that poor nest attentiveness and low incubation temperatures maintained by crested mynas resulted in the low hatching and consequent low fledging success.

The experiments described in this paper show that two species of chickadees learn from one another about the location and nature of potential feeding places when they are foraging together in mixed flocks in large aviaries. In the first experiment, I show that when an individual of one species finds a single food item, members of the other species modify their foraging behavior over the next few seconds so that they put more effort into searching near the site of the find. This applies to both species. Further, members of both species modify their foraging behavior when a bird of the other species searches in a place unsuccessfully. This response to an unsuccessful search is similar to, but weaker than, the response to a food find. The second experiment shows that when the two species are trained to forage in different positions in the experimental trees, they converge in their foraging behavior when they are put in mixed flocks, This is a result of copying. The third experiment shows that individuals of both species are more likely to discover a completely new foraging place if they are in the presence of an experienced bird of the other species.I discuss these results in relation to theories on the adaptive significance of flocking, and conclude that learning about potential feeding places from other species is an important function of mixed flocks, at least for some species. This does not exclude the possibility of other functions of mixed flocks.

Three genera of predacious mites in the subfamily Phytoseiinae (Acarina: Phytoseiidae) are known to occur in Canada and Alaska. Chant reviewed the genus PhytoseiusRibaga in Canada, and Chant and Hansell reviewed the genus AmblyseiusBerlese in Canada and Alaska. The present paper, based on examination of several thousands of specimens, describes, keys, and figures the 20 species of TyphlodromusScheuten known to occur in Canada and Alaska, and includes full collection records. Two new species arc described.

Reproducible live wet weights may be obtained for medium to large larvae of Metriocnemus knabiand Chironomus attenuatusafter blotting them on filter paper for 1 min. To obtain reliable measures of wet weight for smaller larvae the blotting time must be reduced in proportion to the surface area/volume ratio of the larvae. Dry weights are easily obtained by oven drying at 60 °C for 24 h but drying for several days does not affect the results. A temperature of 100 °C decreases die percentage dry matter in C. attenuatus. Both species display an increase in percentage dry matter with increasing size. The extent to which the gut is filled with food has no effect on the percentage dry matter. Attempts to determine dry weight directly from preserved larvae were unsuccessful.

Honey bee studies would be facilitated and extended if a reliable method of rearing honey bees in the laboratory were devised. Most failures in development occur in the postcapping stages. Therefore, fully fed larvae or pupae of all three castes were removed from the comb and reared in the laboratory in various ways to ascertain if the precapping or postcapping techniques were at fault. Developmental failure was measured by an arbitrary "scale of success" in which the prepupal and preimaginal ecdyses were scored according to the distance the skin was shed.Routine handling of the postcapping stages with forceps does not appear to affect development, and exposure to room temperatures and humidities is damaging only to drone larvae and pupae. Hindgut intimae should not be removed by hand. Prepupae and pupae, in natural cells, had high ecdysal scores when held at 20–80% R.H. probably because water vapor loss is reduced by the cell cappings. However, outside the natural cell the postcapping stages can best be reared at 80% R.H. and pupae can also be reared at 60%. The best material on which to rear the bees is paper tissue or surgical gauze. Pupae also rear well in wax grooves or on surgical cotton wool. However, when no cell is used, several abnormalities in development occur.

This paper constitutes a "stocktaking" of biological control in Canada. The success or failure of each of 31 Canadian biological control projects is assessed. Past experiences in Canada are analyzed, and recommendations for future work are made. The meaning of the term "control" is defined in an economic context. Lloyd's (1960) suggestion regarding the influence of host plant longevity on the success of biological control is rejected, and a new concept based on the type of injury inflicted by the pest is substituted. There is a discussion on the philosophy of biological control and some of the popular misconceptions regarding it. Some dangers of biological control are suggested. Smith's (1929) analysis of the population effects of multiparasitism is challenged. The simultaneous introduction of many exotic species of parasites and predators is not favored and a strong plea for more discrimination and caution in the selection of species for introduction is voiced. The need for research in this field is emphasized, and fields of research are suggested. The philosophy of a biological control research program is outlined.

Analyses of the somatic complements of Hylemya antiqua, H. brassicae, H. cilicrura, H. crucifera, H. floralis, H. fugax, H. planipalpus, and H. trichodactyla(?) have been made following techniques described in the first paper of this series. All species, except H. fugax, have 12 chromosomes. These 12-chromosome species fall naturally into three main groups differing in average arm ratios and in other respects. H. fugaxmales have 13 chromosomes and females have 14, both including five pairs of submetacentric autosomes. One to three supernumerary chromosomes were found in a few larvae of H. cilicrura. Small intraspecific differences were found between collections of H. brassicaefrom different geographic locations. The results with this genus emphasize the inaccuracy of referring to complements which look similar as the same or identical.

This investigation is based upon the examination of 205 muskrat carcasses taken at various times between October 1944 and May 1947 and derived from 17 different localities in British Columbia. Seventy-four per cent of these carcasses were parasitized by 13 species of internal parasites. These included: trematodes, Echinostomum coalitum, Echinoparyphium contiguum, Quinque-serialis quinqueserialis, Notocotylus urbanensis, and Plagiorchis proximus; cestodes, Hymenolepis evaginataand Hymenolepis octocoronata; nematodes, Capillaria ransomia, Trichuris opaca, and Hepaticola hepaticaand a species of Acanthocephala, related to the genus Polymorphus(Family Corynosomidae). Two larval cestodes were found infecting the liver; the strobilocercus, Cysticercus fasciolaris(Taenia taeniaformis) and a proliferating cysticercus, Cladotaeniasp. Pathological lesions in the muskrats resulted from two different pulmonary infections, infections of wounds, and a type of tumor. It was found that: the muskrats in this province were not extensively parasitized; hence mortality due to excess parasitism is probably negligible. This paper includes a review of the parasites of the muskrat that have been recorded by other workers.

This paper is a study of base sequence relationships in blackflies by DNA–DNA hybridization. The species used are: Simulium venustum, S. tuberosum, S. vittatum, Cnephia dacotensis, and Prosimulium multidentatum. The midpoints of thermal transition and the buoyant density in CsCl were determined for the DNA of each species and the percent G + C estimated. With the filter method of hybrid formation, maximal yield was obtained at 60 °C; 24 h was found to be a practical length of time for incubation. When the amount of DNA on filter was varied, the homologous reaction reached a plateau at about 50% of the input radioactive DNA; the heterologous reaction reached a plateau at a lesser value in a species-dependent manner. The results indicate a close relationship between S. venustumand S. tuberosum, a more distant one between these species and S. vittatum, and an intermediate one with C. dacotensis. Prosimulium multidentatumshared very little homology with members of the other genera. A precise quantitative evaluation of the results is difficult owing to the complexity of interacting factors. Interpretation would be aided by knowledge of genome sizes and intragenome repetition frequencies. Appropriate studies are underway.

This paper records a discovery of basic, partially independent nuclear units that lie within a common nuclear membrane of some vertebrate cells. The cells concerned are found in series from small (1–2 μ) to large (10–15 μ or more). The smallest cells possess one basic nuclear unit, the larger cells have several. The series of cells from small to large represent stages of a life cycle. Certain of the basic nuclear units act as reproductive organelles and certain large cells are parent cells producing new small cells thus closing one life cycle and starting another. The large cells are formed from the small cells through a series of fusions. The basic nuclear units behave similarly to micronuclei, the reproductive organelles in ciliates, but the fusions of the vertebrate cells are permanent, not temporary unions such as conjugation in ciliates.

This paper deals with the ranges of hares in an area of the Quebec Laurentians which is characterized by a heterogeneity of vegetation structure. The vegetation structures are described, and the relation of the hares to this environment is shown in terms of utilization. Modifications of rates and areas of movements of the hares are correlated to physical and climatic factors. By expanding trap lines from main study areas, and by gang-trapping, social aspects of individuals are studied. Conclusions reached are: (a) vegetation structure plays an important role in determining the ranges of hares; (b) climatic and physical factors dampen or activate movements within the ranges; (c) female hares are consistent in their choice of browse and cover areas whereas males are not; (d) daily ranges of males and females in summer and winter are found to be about 4 acres; (e) modifications of daily ranges of hares are decreases when females care for young, and increases when males move from one female's range to another; (f) the total ranges of males is ultimately determined by the sum of the ranges of the female hares which they court.

This paper describes a bacteriological study of strains of Bacillus cereusFrankland and Frankland producing disease in codling moth larvae and an investigation of their pathogenicity. Strains of the bacterium were pathogenic to the codling moth by feeding or by injection.

Female black flies were taken abundantly in fan traps, on "sticky" mannequins, and on "sticky" flesh-colored paper cylinders when carbon dioxide was released beside them, but few were taken without the carbon dioxide. More flies were taken from the cylinders placed horizontally than vertically and more from the ends of the horizontal cylinders than from the mid-portions. More flies landed on the ends of the vertical cylinders near which the carbon dioxide was escaping than on the opposite ends. Many flies were collected using human breath as a stimulus. Heating the silhouettes did not predictably affect their attractiveness. The combined results indicate that carbon dioxide and vision are especially significant to the orienting and landing of Simulium venustum.

This paper deals with the locomotor movements of four fish species, Salmo gairdnerii irideusGibbons, Ambloplites rupestris rupestris(Rafinesque), Ictalurus nebulosus nebulosus(Le Sueur), and Lepomis gibbosus(Linnaeus), and the locomotor patterns displayed by non-conditioned animals in constant conditions of light and darkness.The entries into the 16 sectors of the tank were uniformly distributed; there was no preference shown by the fish for any one sector of the experimental tank, regardless of the light condition.Most animals with the exception of the rock bass displayed a definite pattern of locomotor movements, consisting of a range of turning angles. Variations in this pattern were not significant from day to day under similar experimental conditions of light.Frequencies of right- and left-handed turns showed individual differences in a large number of bullhead and pumpkinseed, whereas there were no differences in rock bass. Thigmotaxis and vision might play a role in this turning behavior.Animals displayed a different angular pattern of locomotion under light and dark conditions. Rock bass and pumpkinseed showed a preference for short angle turns whereas rainbow trout made turns of longer angles. Bullhead showed no change in the magnitude of the angles of turn.

Retinae of fish exposed to 9 × 102 ft-c are more fully adapted to light than those of fish exposed to 10−1 ft-c. Retinae of the former group take a shorter time to attain the same state of adaptation as that of the latter. However, they take a longer time than the latter to attain their own maximum state of adaptation. Retinae of fish subjected to darkness after exposure to 9 × 102 ft-c are not dark-adapted even after 70 minutes. The retinal epithelial pigment of fishes placed in darkness from light of 10−1 ft-c dark-adapts in 45 minutes while the cones do so in 25 minutes. The retinal index indicates that dark-adaptation occurs 45 minutes after subjection to dark. Hypotheses presented in a previous paper are discussed in the light of these results.

The somatic chromosome complements of nine sarcophagid species are described using methods presented in the first paper of this series. These species are Acridiophaga aculeata, Kellymyia kellyi, Protodexia australis, P. hunteri, Pseudosarcophaga affinis, Sarcophaga aldrichi, S. cooleyi, Sarcophaga"H", and S. reversa. P. affinishas 19 or 20 chromosomes whereas all the others have 12-chromosome complements most of which can be distinguished.

The authors have studied the hypopial nymphs (Acarina, Sarcoptiformes) living in phoretic association with mammals in Canada. So far only two species have been recorded from Canada. In the present paper six additional species are recorded and among these one is new and is described here.

During 1952–54, fishes were collected and examined for parasites (particularly those of the blood and gills) at various localities ranging from Sydney, Australia, through the island groups of Melanesia to Tarawa, Gilbert and Ellice Islands Colony. Most of the specimens were obtained by poisoning intertidal zone pools on coral reefs or rocky coasts, the remainder being from fresh-water or brackish sources. A total of 1121 fishes of at least 122 species, 63 genera, and 27 families were dealt with. This paper, the first of a series detailing the findings, includes a complete list of the material, an account of the techniques employed, and new host and locality records for Haemogregarina bigeminaLaveran and Mesnil and H. mugiliCarini.

This paper presents the continuation of studies on blood cell behaviors published earlier by Engelbert.It was then shown that "nuclear bodies" named "basic nuclear units" passed through several stages of a nuclear life history which was believed to hold the key to blood cell cytogenesis. Blood cell polymorphism or pleomorphism is believed to be products of the many staged nuclear life history. The nuclear life history can be experimentally altered, for example by foreign proteins. The basic nuclear units are believed to be reproductive organelles.Additional evidence of nuclear behaviors fitting into the nuclear life history is presented. Formation and release of vesicles by myeloblast nuclei was demonstrated earlier. Evidence is presented here to show that the production and release of these intranuclear vesicles is not a sign of degeneration, but a process by which new cells can be produced through reassociation of released nuclear materials. Some released vesicles become red blood cells. Extreme variations in shape of myeloblast nuclei are not signs of degeneration, but are characteristic nuclear behaviors associated with nuclear activity.The release of new small nuclei, intranuclear vesicles, and various granules are nuclear activities leading to formation of new cells.

In this fourth and final paper on the monogenetic trematodes from the Bay of Quinte area, Ontario, the genus DactylogyrusDiesing, 1850 is studied. Host–parasite and the parasite–host lists of the monogenetic trematodes recovered during the entire survey are presented.

In the present, the third in a series of papers on Monogenea from the Bay of Quinte area, 20 species of the subfamily Ancyrocephalinae Bychowsky, 1937 and one species of the family Tetraoncidae Bychowsky, 1957 are presented. The 21 species of the monogenetic trematodes collected are as follows: Actinocleidus fusiformis(Mueller, 1934) Mueller, 1937, A. gibbosusMizelle and Donahue, 1944, A. mizelleisp. n., A. recurvatusMizelle and Donahue, 1944. Cleidodiscus alatusMueller, 1938, C. capaxMizelle, 1936, C. glenorensissp. n., C. priceiMueller, 1936, C. robustusMueller, 1934, C. stentorMueller, 1937, C. vancleaviMizelle, 1936, Urocleidus acer(Mueller, 1936) Mizelle and Hughes, 1938, U. adspectusMueller, 1936, U. dispar(Mueller, 1936) Mizelle and Hughes, 1938, U. feroxMueller, 1934, U. fundulusMizelle, 1940, U. furcatus(Mueller, 1937) Mizelle and Hughes, 1938, U. hargisisp. n., U. principalis(Mizelle, 1936) Mizelle and Hughes, 1938, U. rogersisp. n., and Tetraoncus monenteronDiesing, 1858. Descriptions and drawings of the new species and comprehensive measurements of the remaining species are presented.

The metacercarial stage of Gymnophalloides tokiensishas a mid-ventral pit which was mistaken in the original description for a wide genital pore. The genital pore is small, on the anterior edge of the ventral sucker, and not surrounded by prominent muscle fibers. Other corrections of the original description include paired, compact vitellaria (referred to as Mehlis gland), a bipartite (not globular) seminal vesicle, and an ovary smaller than the testes; no eye spots or a seminal receptacle are present.Yamaguti's (1971) synonymy of LacunovermisChing, 1965 with Gymnophalloidesis rejected because of the differences in the location and type of genital pore. In contrast to G. tokiensis, both L. conspicuusand L. macomae(Lebour, 1908) Loos-Frank, 1970 have a wide genital pore that opens some distance from the ventral sucker and both ventral pit and genital pore are surrounded by strong muscle fibers.Two of Yamaguti's (1971) footnotes about gymnophallid trematodes are corrected. In my 1965 paper, I did not synonymize Gymnophalloideswith Meiogymnophallusbut replaced Gymnophalloidesas emended by James (1964) with the name Meiogymnophallus. I did not synonymize Gymnophallus oidemiae, now M. minutus(Cobbold, 1859) Bowers and James, 1967, with G. somateriaebut regard them as distinct species.

Kieffer's genus Lasioheleais now recognized as an association of subgenera of Forcipomyiahaving in common an elongated second radial cell in the wing. Tokunaga separated two of the component subgenera of this Lasioheleacomplex, using adult characters. The present paper introduces the evidence of the early stages, adding six new species to the subgenus Lasiohelea, four to Neoforcipomyia, and one to Warmkea.

New Brunswick outbreaks of the spruce budworm which began in 1912 and 1949 are considered in relation to the theory of climatic release. Studies on a natural population show that larval development is more rapid in dry and sunny weather than in humid and cloudy weather. Polar air masses bring the favorable conditions, and tropical air masses and cyclones the unfavorable. June precipitation and temperature records, analyzed in conjunction with weather maps, show that climatic changes took place in regions where the outbreaks developed. The outbreaks were preceded by dry and sunny summers during four or five consecutive years. Although direct mortality of the budworm due to adverse weather conditions has not been observed, favorable climatic conditions may have indirectly promoted population increase from the endemic to the outbreak level in the following ways. Flower production became more frequent in periods of dry years and larvae which fed on staminate flowers developed more rapidly. Larvae that developed early in the season gave rise to more fecund females than larvae that developed late. The age of current foliage consumed is also related to fecundity. The rate of development of balsam fir relative to the budworm varies from year to year. It is postulated that the average fecundity of the budworm increases in the pre-outbreak years as the result of favorable climatic conditions and greater than usual flower production. Larval mortality is greater in years with a prolonged developmental period although the increase is not statistically significant. The theory that outbreaks in New Brunswick resulted from the spread of populations from outbreak areas to the west will be considered in the second part of this two-part paper.

Larvae of Cephus cinctuswere held at constant temperatures between −15 and −30 °C and the incidence of freezing was recorded. A linear relation with high correlation coefficient was obtained when the logarithm of mean freezing time was plotted against temperature. Mean time to freeze doubles with each 0.53° rise in temperature; within the range studied, it increased from 1.2 seconds at −30° to more than a year at −17°.A family of freezing curves showing the course of freezing at a series of constant temperatures permits approximation of the course of freezing during a regime of fluctuating temperatures such as would occur naturally in hibernacula.From this paper and two preceding ones by the writer, it is now apparent that the general temperature range within which an insect nucleates and freezes is determined by intrinsic factors (nucleating agents and body water), whereas the specific freezing temperature within this range is determined by extrinsic factors (cooling pattern and the element of chance that attends nucleus formation.)

This paper contains a taxonomic survey of nematodes belonging to the predaceous family Mononchidae, collected by Dr. Fields Caveness in western Nigeria during 1959–61. Four genera, new to science, Crassibucca, Hadronchus, Polyonchulus, and Prionchulellus, and 16 new species, Crassibucca penicula, C. macrocauda, C. microdonta, Hadronchus bisexualis, H. monohystera, Iotonchus acuticaudus, I. clarki, I. nigeriensts. I. parabasidontus, I. tarjani, Miconchus pararapax, M. thornei, Mylonchulus curvicaudus, Polyonchulus cobbi, P. megadontus, and Prionchulellus cavenessiare described and illustrated.Several already described species are also included. Iotonchus piracicabae(Lordello) and Mononchus(I.) piracicaboidesCarvalho are placed in synonymy of I. trichurus(Cobb). Miconchus dadayi(Micoletzky) inSchneider, 1953 is considered a synonym of Miconchus pararapaxn. sp. Miconchus dadayi(Micoletzky, 1914), (=Mononchus macrostomaof Daday, 1910) is regarded as species inquirenda. Mylonchulus hawaiiensis(Cassidy) is removed from synonymy, and Iotonchus similis(Cobb) is designated incertae sedis. Mylonchulus montanus(Thorne) is considered a synonym of Mylonchulus lacustris(Cobb). An illustrated taxonomic key to the 14 genera in the family Mononchidae is presented. Keys to most of the world species in these genera are also included.The value of the tuberculate and non-tuberculate valve as a generic character is discussed.