Absence Of Mating Research Articles

Caenorhabditis elegansUNC-103 ERG-Like Potassium Channel Regulates Contractile Behaviors of Sex Muscles in Males before and during Mating

During mating behavior the Caenorhabditis elegans male must regulate periodic and prolonged protractor muscle contractions to insert his copulatory spicules into his mate. The protractors undergo periodic contractions to allow the spicules to reattempt insertion if a previous thrust failed to breach the vulva. When the spicule tips penetrate the vulva, the protractors undergo prolonged contraction to keep the spicules inside the hermaphrodite until sperm transfer is complete. To understand how these contractions are regulated, we isolated EMS-induced mutations that cause males to execute prolonged contraction inappropriately. Loss-of-function mutations in the unc-103 ERG-like K(+) channel gene cause the protractor muscles to contract in the absence of mating stimulation. unc-103-induced spicule protraction can be suppressed by killing the SPC motor neurons and the anal depressor muscle: cells that directly contact the protractors. Also, reduction in acetylcholine suppresses unc-103-induced protraction, suggesting that UNC-103 keeps cholinergic neurons from stimulating the protractors before mating behavior. UNC-103 also regulates the timing of spicule protraction during mating behavior. unc-103 males that do not display mating-independent spicule protraction show abnormal spicule insertion behavior during sex. In contrast to wild-type males, unc-103 mutants execute prolonged contractions spontaneously within sequences of periodic protractor contractions. The premature prolonged contractions cause the spicules to extend from the male tail before the spicule tips penetrate the vulva. These observations demonstrate that unc-103 controls various aspects of spicule function.

Acceleration of oviductal transport of oocytes induced by estradiol in cycling rats is mediated by nongenomic stimulation of protein phosphorylation in the oviduct.

In order to explore nongenomic actions of estradiol (E2) and progesterone (P4) in the oviduct, we determined the effect of E2 and P4 on oviductal protein phosphorylation. Rats on Day 1 of the cycle (C1) or pregnancy (P1) were treated with E2, P4, or E2 + P4, and 0.5 h or 2.5 h later their oviducts were incubated in medium with 32P-orthophosphate for 2 h. Oviducts were homogenized and proteins were separated by SDS-PAGE. Following autoradiography, protein bands were quantitated by densitometry. The phosphorylation of some proteins was increased by hormonal treatments, exhibiting steroid specificity and different individual time courses. Possible mediation of the E2 effect by mRNA synthesis or protein kinases A (PK-A) or C (PK-C) was then examined. Rats on C1 treated with E2 also received an intrabursal (i.b.) injection of alpha-amanitin (Am), or the PK inhibitors H-89 or GF 109203X, and 0.5 h later their oviducts were incubated as above plus the corresponding inhibitors in the medium. Increased incorporation of 32P into total oviductal protein induced by E2 was unchanged by Am, whereas it was completely suppressed by PK inhibitors. Local administration of H-89 was utilized to determine whether or not E2-induced egg transport acceleration requires protein phosphorylation. Rats on C1 or P1 were treated with E2 s.c. and H-89 i.b. The number and distribution of eggs in the genital tract assessed 24 h later showed that H-89 blocked the E2-induced oviductal egg loss in cyclic rats and had no effect in mated rats. It is concluded that E2 and P4 change the pattern of oviductal protein phosphorylation. Estradiol increases oviductal protein phosphorylation in cyclic rats due to a nongenomic action mediated by PK-A and PK-C. In the absence of mating, this action is essential for its oviductal transport accelerating effect. Mating changes the mechanism of action of E2 in the oviduct by waiving this nongenomic action as a requirement for E2-induced embryo transport acceleration.

Vasopressin in the lateral septum regulates pair bond formation in male prairie voles (Microtus ochrogaster).

Male prairie voles (Microtus ochrogaster) form a pair bond with a female partner after mating, and this behavior is regulated by the neuropeptide vasopressin (AVP). The authors report that AVP in the lateral septum is important for pair bond formation. Administration of an AVP V1a receptor antagonist in the lateral septum blocked mating-induced pair bonding, whereas administration of AVP induced this behavior in the absence of mating. In addition, administration of an oxytocin (OT) receptor antagonist in the lateral septum also blocked pair bond formation induced by either mating or AVP administration, suggesting that the OT receptor blockade may have interfered with the AVP regulation of behavior. Together, these data provide evidence suggesting that AVP in the lateral septum regulates pair bond formation in male prairie voles and that this process requires access to both AVP and OT receptors.

Dopamine D2 receptors in the nucleus accumbens are important for social attachment in female prairie voles (Microtus ochrogaster).

The prairie vole (Microtus ochrogaster), a monogamous rodent that forms long-lasting pair bonds, has proven useful for the neurobiological study of social attachment. In the laboratory, pair bonds can be assessed by testing for a partner preference, a choice test in which pair-bonded voles regularly prefer their partner to a conspecific stranger. Studies reported here investigate the role of dopamine D2-like receptors (i.e., D2, D3, and D4 receptors) in the nucleus accumbens (NAcc) for the formation of a partner preference in female voles. Mating facilitated partner preference formation and associated with an approximately 50% increase in extracellular dopamine in the NAcc. Microinjection of the D2 antagonist eticlopride into the NAcc (but not the prelimbic cortex) blocked the formation of a partner preference in mating voles, whereas the D2 agonist quinpirole facilitated formation of a partner preference in the absence of mating. Taken together, these results suggest that D2-like receptors in the NAcc are important for the mediation of social attachments in female voles.

Candida batistae, a new yeast species associated with solitary digger nesting bees in Brazil

Several strains of the new yeast species Candida batistae have been isolated from larval provisions, larvae, and pupae of the solitary bees Diadasina distincta and Ptilotrix plumata (Apidae) in Minas Gerais, Brazil. Candida batistae was the predominant species in the yeast community associated with this habitat, where it often co-occurred with a yeast form of Mucor sp. It is thought that these two organisms play a role in the maturation of beebread. The new asexual ascomycetous yeast is related to Starmerella bombicola and other floricolous Candida species, as evidenced by their nutritional profiles and the sequences of the D1/D2 domains of their large subunit ribosomal DNAs. Identification characteristics are similar to those of S. bombicola, but the species can be separated on the basis of some physiological characters and absence of mating with haploid strains of that species. The type culture is strain UFMG96-Y192 (CBS 8550).

Purification of Sxa2, a carboxypeptidase involved in pheromone recovery in fission yeast.

The fission yeast Schizosuccharomyces pombe exists in one of two mating types (Plus or Minus) and conjugation between two haploid cells is controlled by the reciprocal action of diffusible mating pheromones (for review, see 1). Thus, a P-cell releases P-factor and responds to M-factor since it expresses the M-factor receptor while an M-cell releases M-factor and responds to P-factor. Exposure to pheromone causes changes that prepare the cell for mating. In the absence of mating, however, the cell recovers from the effects of the pheromone and resumes normal mitotic growth (2.3). One approach to understanding this recovery is to characterise mutants that are defective in their ability to adapt to the presence of the pheromone.

Natural Versus Chorionic Gonadotropin-Induced Ovarian Responses in the Clouded Leopard (Neofelis Nebulosa) Assessed by Fecal Steroid Analysis1

The clouded leopard (Neofelis nebulosa) is an endangered species difficult to propagate in captivity because of sexual incompatibility between paired individuals. Fecal estradiol (E2) and progesterone (P4) metabolites were quantified in 14 females to noninvasively monitor seasonal reproductive patterns and compare ovarian responses to natural mating vs. exogenous gonadotropins. Increased E2 excretion was associated with behavioral estrus or eCG treatment, whereas elevated P4 metabolites were observed during natural and hCG-induced pregnant and nonpregnant luteal phases. On the basis of fecal E2 profiles, duration of the estrous cycle was 24 +/- 2 days, with estrus lasting 6 +/- 1 days. Mean gestation length was 89 +/- 2 days, whereas duration of the nonpregnant luteal phase was 47 +/- 2 days. Females experienced a seasonal anestrus during the late summer and early fall. One female demonstrated a lactational anestrus after the birth of three cubs. On nine occasions, clouded leopards ovulated spontaneously (based on elevated fecal P4 metabolite concentrations) in the absence of mating. Patterns of eCG-stimulated E2 excretion were similar to those associated with natural estrus and were unaffected by eCG dosage (25, 50, or 100 IU). In contrast, post-hCG P4 metabolite profiles varied considerably, with responses including anovulation, attenuated luteal P4 metabolite production, and hyperstimulated luteal function. In some females, compromised luteal function after ovulation induction appeared to be due to the presence of mature CL from previous spontaneous (without copulation) ovulations at the time of gonadotropin treatment. Duration of post-hCG P4 metabolite excretion was reduced approximately 40% in these individuals compared to females with no evidence of active luteal activity. In sum, these are the first data describing the ovarian cycle of this endangered species. The information is important because it is based on the longitudinal assessment of multiple females using a completely atraumatic approach, thereby eliminating the potential confounding impact of stress. Data indicate that spontaneous ovulations and the presence of active luteal tissue on the ovary can profoundly affect ovarian responses to exogenous gonadotropin therapy. Therefore, fecal steroid monitoring can serve as a useful adjunct to developing assisted reproduction techniques, especially the hormonal induction of ovulation for planned artificial insemination.

The expression of the immediate-early genes c-fos, egr-1 and c-jun in the accessory olfactory bulb during the formation of an olfactory memory in mice

Female mice form a memory for the pheromones of the male with which they mate. It has been proposed that the site of the synaptic changes underlying this memory is the accessory olfactory bulb, at the first level of the accessory olfactory system. In this study we have examined the expression of the immediate-early genes c-fos, c-jun and egr-1 in the mitral and granule cells of the accessory olfactory bulb immediately after mating, during the period of memory formation. Transient increases were seen in the number of granule cell nuclei expressing c-fos and the number of granule and mitral cell nuclei expressing egr-1, during the period of memory formation. No changes were observed in the expression of c-jun during this period. The increase in the number of cells expressing c-fos and egr-1 required the association of mating and pheromonal exposure, conditions also required for memory formation. Large increases in the number of mitral and granule cell nuclei expressing c-fos and egr-1 were also observed following the infusion of the drug bicuculline into the accessory olfactory bulb in the absence of mating. This procedure has previously been shown to result in the formation of a nonspecific memory for male pheromones. These results associate the expression of c-fos and egr-1 in the accessory olfactory bulb with the conditions required for the formation of an olfactory memory for male pheromones.

Partner preference development in female prairie voles is facilitated by mating or the central infusion of oxytocin.

Results of these experiments indicate that females given at least 24 hours of cohabitation with a male develop a social preference for the familiar partner versus a stranger. Mating is not essential for the development of partner preferences, but clearly facilitates the onset of preferences. Females given six hours of cohabitation showed partner preferences only if they mated with the partner during cohabitation (Experiment 2) or if they received oxytocin (Experiment 3). Females that continued to mate during preference tests (Experiment 2, n = 4) mated exclusively with the partner. Oxytocin infusions, even in the absence of mating or estrogen priming, facilitated the development of partner preferences.

Influence of Male Competition and Female Mate Choice On Male Mating Success in Barbary Macaques (Macaca Sylvanus)

AbstractTo evaluate the importance of male competition and female mate choice for male mating success in Barbary macaques, focal female observations during the conceptional estrus were conducted in a large semifree-ranging group. Analysis of sexual behaviour included 121.7 h of observation of 19 focal females. In addition, ad libitum recorded male agonistic interactions, occurring in the vicinity of the focal females, were analyzed. Both sexes initiated sexual associations, and females were found almost always in contact (within 2 m) with a male. Most matings took place within 1 min after contact establishment, and the proportion of these quick matings was especially high for subadult males, which mainly "sneaked" copulations during moments of distraction of adult males. Mating contacts were longer than non-mating contacts, and varied in duration from a few seconds to more than 2 hours. Mating contacts with adult males did not differ in length with respect of the initiating sex. Females were considerably more active in terminating than initiating contacts. Females mated, on average, once every 30 min, and had 1-10 different partners (out of 37 sexually mature males) during a 4 h observation session. Females mated with 40-100% of their contact partners. An absence of mating with specific males was due to interference by other males, improper timing of contact, or (temporary) lack of attractivity of the female rather than related with a rejection of these males in almost all cases. Similarly, a highly significant positive correlation between mating frequency of a male and time spent in the vicinity of the focal females revealed that females did not discriminate among potential mates, and, hence, did not exercise mate choice. The majority of matings (71 %) were accumulated by 7 out of the 9 oldest males and additionally 2 young adults. One indicator for sexual competition among males was the peak of male injuries during the mating season. Aggressive interactions between adult and subadult males, indicating a clear-cut dominance of the adults, occurred frequently, while dyadic agonistic interactions between adult males were rare and inconsistent. The available data indicated age-inversed rank relations and were not predictive for mating success. A highly significant positive correlation was, however, found between male mating success and the participation as ally in polyadic agonistic interactions. The oldest males gave and received most support and were rarely victims of coalitions while the reverse was found for young adult males. All males followed an "age rule", after which the older of 2 males was supported during a conflict. Consequently, male power asymmetry in polyadic conflicts ran counter that in dyadic situations, and could change quickly depending on the presence of potential allies. Chances for dyadic solutions of conflicts were rare on the ground where most estrous females and the old males spent their time. Although females did not reject potential mates, they nevertheless influenced male mating success by inciting male competition. Females often tried to contact a new partner after a mating, thereby actively putting both males into conflict. The creation of such encounters was possible only between males with low power asymmetry, and only males which got successfully through these frequent female-initiated tests of their power had a high mating success. Incitation of male competition was discussed as a female mating tactic in species with a high sexual dimorphism. Compared with other macaques, the Barbary macaque belongs to such species.

Individual variation in the neural timing of infanticide and parental behavior in male house mice

In male house mice ( Mus domesticus and M. musculus), the act of coital ejaculation provides a fail-safe neural signal for timing the birth of their offspring. A unique aspect of this phenomenon is the extraordinary latency that can occur between the stimules (ejaculation) and its adaptive neural response (male mice cease killing pups and behave parentally toward them). Thus the inhibition of infanticide is routinely time-delayed for many days after mating. In the absence of mating, cohabitation with a female will not inhibit infanticide in CF-1 stock males ( M. domesticus), whereas the birth of pups in the male's home cage will inhibit infanticide. But with regard to the ejaculatory phenomenon, which also includes the spontaneous reemergence of infanticide 50–60 days after mating, this entire bahavioral cycle toward pups can occur in the total absence of regular time cues from a light/dark cycle following ejaculation. However, exposure to photoperiodic (L:D 12:12) or constant light (LL) accelerated the transition time from infanticide to parenting after ejaculation, while in constant dark (DD), the transition time to parenting was significantly prolonged. The time interval between ejaculation and the inhibition of infanticide, which varied among individuals first mated at 6 months of age, was repeatable when the same males were remated at 9 months of age; however, when males were again mated at 18 months of age, the time interval between ejaculation and parenting was dramatically prolonged. In general coital ejaculation triggers a neural timing system that cannot be explained by any presently known physiological mechanism. Our results do suggest, however, that the neural timing variation observed among individuals is influenced by sex steroid exposure during late fetal development.

Confirmation of ovulation and characterization of luteinizing hormone and progesterone secretory patterns in cycling, isosexually housed Bolivian squirrel monkeys (Saimiri boliviensis boliviensis)

In the female Bolivian squirrel monkey a much greater elevation of serum estradiol (E2) was measured after mating than that observed in similary cycling monkeys that did not mate. This raised the possibility that cycling squirrel monkeys may not ovulate during nonmated cycles To test this hypothesis, we performed laparoscopies on nine isosexually housed, cycling monkeys to observe the ovaries after the luteinizing hormone (LH) surge, which was measured by mouse interstitial cell bioassay using LER 1909-2 as the standard. Single ovulatory stigmas were identified as well demarcated, red, punctate depressions at the center of dome-shaped elevations on the ovarian surface in eight monkeys, when laparoscopically examined 9-56 hr after the LH peak. One monkey examined laparoscopically prior to the LH surge had a large translucent cystic follicle, confirming the morphology of the mature prevulatory follicle. Mean progesterone (P) concentrations fell to a nadir 1 day prior to the LH surge and then began to rise on the LH surge. Peak P levels were found 2 days after the LH surge. In the ovulating animals in which periovulatory E2 levels were measured, no value was greater than 800 pg/ml, indicating that the presence of follicular rupture was not sufficient to account for the elevated E2 levels observed after mating. These data confirm ovulation and follicular rupture in the absence of mating and delineate the relationship between periovulatory LH, P, and E2 secretory patterns in cycling squirrel monkeys.

Some aspects of oögenesis in the stable fly Stomoxys calcitrans (Diptera: Muscidae)

Two distinct patterns of blood ingestion in the female stable fly, Stomoxys calcitrans L. were observed, based on whether or not the female was mated. Mating is not required for oögenesis, but is necessary for oviposition. Virgin females develop eggs but, in the absence of mating, they retain eggs until death. In stable flies, oögenesis appears to be atypical among other dipterans as the penultimate follicles develop and deposit up to 50% yolk before the terminal follicles are matured. Oösorption was seen in the penultimate follicles of virgin females retaining eggs. Accessory-gland implants initiated oviposition in virgin females. However, the total number of eggs laid by such females was 50% less than the number of eggs laid by mated flies.

Viability of Physarum polycephalum spores and ploidy of plasmodial nuclei.

Amoebae of Physarum polycephalum carrying the mth mating-type allele may differentiate into plasmodia in the absence of mating. Such plasmodia are haploid and, upon sporulation, produce mainly inviable spores. We have asked whether the viable spores arise from meiotic or mitotic divisions. Using a microfluorometric measurement of the deoxyribonucleic acid content of individual nuclei, we found the fraction of viable spores to be correlated with the proportion of rare, diploid nuclei containing in the generally haploid plasmodium. When homozygous diploid plasmodia were created by heat shocking, spore viability increased dramatically. We suggest that viable spores are produced via meiosis in mth plasmodia, that the mth allele has no effect on sporulation per se, and that the normal source of viable haploid spores is a small fraction of diploid nuclei ubiquitous in haploid plasmodia.

Haemaphysalis (Kaiseriana) mageshimaensis sp. n. (Ixodoidea: Ixodidae), a Japanese Deer Parasite with Bisexual and Parthenogenetic Reproduction

Haemaphysalis (Kaiseriana) mageshimaensis sp. n., a member of the H. (K.) bispinosa group, is described from males, females, nymphs, and larvae from pasture vegetation (and laboratoryreared) from Mage Island in Kagoshima Prefecture, Japan. The sika deer, which is common on Mage Island, appears to be the original host. Most of the cattle on the island are infected by Theileria sp., which is probably transmitted by this tick. In the laboratory, the life cycle is completed in 93 to 108 days. Normal bisexual reproduction, with 1,000 to 1,500 eggs per female, almost 100 per cent larval hatching, and approximately equal numbers of F1-F3 males and females, was observed, as well as an appreciable though limited degree of true parthenogenetic reproduction, with few eggs, low larval hatching rate, absence of mating, and only female F1 adults. No males of this species mated with bisexual or parthenogenetic females of H. (K.) longicornis Neumann. Male longicornis mated with female mageshimaensis, but four or five days after mating almost all sperm had disappeared from female organs, the larval hatching rate was low, and all progeny consisted of mageshimaensis females. Haemaphysalis (K.) mageshimaensis sp. n., from a Japanese island with a subtropical or temperate climate in the eastern part of the Palearctic Faunal Region, is a member of the H. (K.) bispinosa group (Saito and Hoogstraal, 1972) which originated in tropical forests of the Oriental Faunal Region. This new species is noteworthy in that it may reproduce either bisexually or parthenogenetically. A related species, H. (K.) longicornis Neumann of Japan and nearby areas of continental Asia (Hoogstraal et al., 1968), reproduces chiefly parthenogenetically in the northern area of its range and chiefly bisexually in the southern area. Interbreeding between parthenogenetic and bisexual populations of H. (K.) longicornis is unknown. Received for pubpication 19 January 1973. *From Research Project MF33.0524.009-3010B, Bureau of Medicine and Surgery, Department of the Navy, Washington, D. C. The opinions and assertions contained herein are the private ones of the authors and are not to be construed as official or as reflecting the views of the Department of the Navy or of the naval service at large. The illustrations in this report were prepared under the auspices of Agreement 03-005-1 between the NIAID (NIH) and NAMRU-3. t Medical Zoology Department, Niigata University School of Medicine, Niigata City, Japan. t Medical Zoology Department, U. S. Naval Medical Research Unit Number Three (NAMRU-3), U. S. Interests Section, c/o Spanish Embassy, Cairo, Arab Republic of Egypt. Parthenogenesis does not appear to occur in other Haemaphysalis species and may be an adaptation to the cool climate inhabited by these two members of a group that otherwise exists only in a tropical environment. Haemaphysalis (Kaiseriana) mageshimaensis sp. n. Mage Island haemaphysalid

Seasonal variation in fertility in Merino ewes : the reproductive wastage associated with mating in winter, spring, summer, or autumn

Merino ewes of four groups were joined for mating in winter, spring, summer, or autumn. Each group remained with the rams for 8 weeks. Some of the ewes were examined at autopsy 4 weeks after mating, others radiographically 12–18 weeks after mating, and others were allowed to lamb without interference. Some ewes failed to mate in winter and many in spring, but virtually all mated in summer and autumn. In spring, but not in other seasons, some rams served more ewes than others. In winter, but again not in other seasons, the incidence of mating was related to the physical condition of the ewes. Absence of mating, both in winter and spring, was due to ovarian inactivity. There was significant variation between rams in returns to service and in foetal loss 4 weeks after mating. Where fertility of rams was not implicated there was no significant seasonal variation in foetal loss at 4 weeks; this averaged 13% and there was little foetal loss thereafter. Lamb losses were high from ewes mated in summer or autumn but low from those mated in winter or spring.

Oviposition and length of adult life in Caryedon gonagra (F.) (Col., Bruchidae)

Oviposition and the length of adult life in the Bruchid beetle Caryedon gonagra (F.), an important pest of unshelled groundnuts (Arachis) in West Africa, were studied in continuous darkness in incubators at 30 and 40°C. at relative humidities of 50, 70 and 90 per cent., and at 45°C. and 70 per cent., and also under conditions of diurnal alternation of periods of light and darkness in a constant-temperature room at about 27·5°C. and 75 per cent. R.H. Newly emerged beetles were placed, singly (unmated or after a single mating) or in pairs, in tubes with 1–5 unshelled groundnuts. In addition, the influence of the absence of groundnuts was investigated.Length of life of the adults increased with decreasing temperature, increasing relative humidity, the absence of nuts (for females only) and the absence of mating (for females, and, in absence of nuts, for males). Adults survived for 3–4 days at 45°C. and 70 per cent. R.H. Optimum conditions are probably about 27·5—30°C. and 70—90 per cent. R.H., under which the adult length of life was about 21 days.The adults were sexually mature on emergence from the cocoons, and mating took place within 24 hours of emergence. Under the conditions of the experiments, the preoviposition period was between 24 and 48 hours. At 27·5 and 30°C., the mean length of the oviposition period (9—13 days) was only slightly influenced by relative humidity, being slightly shorter at the lowest R.H. (50%); an increase in temperature from 30 to 40°C. caused a marked reduction in the period.About 80 per cent, of the eggs were laid in crevices in the shell of the nut, where they are difficult to find. In the absence of nuts, the females laid readily between the cork and the glass and at the bottom of the tube.At 40°C., oviposition was inhibited at 50 and 70 per cent. R.H., but at 90 per cent. R.H. many eggs (but significantly fewer than at lower temperatures) were laid; the largest mean numbers (106–115) were laid at 27·5–30°C. and 70–90 per cent. R.H.; absence of nuts did not influence the numbers of eggs laid, but caused some irregularity in the oviposition pattern. More than one copulation appeared to be necessary for the female to lay a full complement of eggs.Under conditions of alternating periods of light and darkness, there was a daily rhythm of oviposition, with a strong correlation between numbers of eggs laid and the periods of darkness.The results are compared with those recorded in the literature.

III. The Reproductive Processes of Certain mammals *— Parts IV and V. Part IV. The oestrous cycle of the grey squirrel (Sciurus carolinensis)

Although, it is abundant in many parts of England and of economic importance, singularly little seems to be known about the breeding habits of the grey squirrel (Sciurus carolinensis).Middleton (1930) noted that 23 females examined in March and April, 1930, were non-pregnant, although the males were sexually active. Records of litter size quoted by Middleton suggest that four to six is usual. Apparently no true hibernation occurs in the grey squirrel and this species appeared to be very suitable for the extension of oestrous cycle work. Collection of field material was started in October, 1930. In view of the obvious limitations of such material, attempts were immediately made to induce the animals to breed in the laboratory. These were unsuccessful and although some few animals showed signs of approaching oestrus, no pregnancy or ovulation was obtained. Since better quarters are now available, it is hoped that further information may be secured by observation of animals breeding under laboratory conditions. Such information would relate mainly to the time relations of the cycle and to the nature of the changes in the absence of mating.