ALBERT

Description: Four experiments dealing with attempts to induce pregnancy in the anoestrous ewe during the summer of 1948 are described. While little has been accomplished towards a practical solution of the problem of regularly inducing such pregnancies, some light has been thrown on reasons for past failures and erratic results. The following conclusions are drawn:1. In the absence of a spontaneous corpus luteum, ovulation without heat may be induced in anoestrus by 800 i.u. PMS.2. In the presence of a waning corpus luteum ovulation with heat may be induced in anoestrus by 800 i.u. PMS.3. In the presence of an active corpus luteum neither ovulation nor heat is induced in anoestrus by 800 i.u. PMS. Occasionally, however, heat may occur without ovulation and with the formation of grossly cystic ovaries.4. In mid-anoestrus ovulation is not regularly induced by 800 i.u. PMS, due presumably to very low pituitary and ovarian activity.5. Anoestrus in the ewe is a relative rather than an absolute quiescence, and it is suggested that there is a rhythm of pituitary activity roughly inversely related to the daylight/dark rhythm, deep anoestrus occurring about the time of the longest day. Thus at different stages of anoestrus, different response to the same treatment may be expected in accordance with the proportion of animals falling into the categories 1–4 above.6. Artificially formed corpora lutea are apparently perfectly normal as regards size, colour and function.7. Treatment with PMS alone is sufficient to cause follicular maturation, ovulation and corpus luteum formation. There is some evidence, however, that the anoestrous ewe has some difficulty in ovulating all the follicles matured. The subcutaneous use of Prolan does not alleviate this difficulty, but injection of stilboestrol at about the time ovulation is due, may have some effect.8. The mean ovulation rate of ewes ovulating after 800 i.u. PMS is usually rather higher than the normal for the breed and many cases of definite multiple ovulation have been observed. For this to occur the presence of an old corpus luteum is not necessary. A maximum of six ova have been shed.9. In mid-anoestrus Welsh ewes show a higher resistance to PMS action than do Suffolks, both as regards numbers ovulating and ovulation rates of those responding.10. Injection of PMS in increasing divided doses is no more effective in inducing heat than is a single injection. Ovulation without heat occurs as soon as a certain threshold of stimulation (probably about 400 i.u.) is reached.11. Previous findings have been confirmed that, unless modified by the presence of a spontaneous corpus luteum, ovulation will normally occur within 48 hr. of injection.12. When 35 mg. testosterone propionate is administered 24 hr. before 800 i.u. PMS, heat, usually without ovulation, will occur in a high proportion of ewes. Where ovulation does occur it rarely coincides with heat.13. When testosterone propionate is injected with or after PMS the results are much more variable, depending upon whether or not it is absorbed in time to play a role.14. Testosterone propionate, while inhibiting ovulation, does not inhibit follicular development.15. Testosterone propionate has no oestrogenic effect. Its action in inducing oestrus in conjunction with PMS has been discussed.16. The low percentage recovery of fertilized ova following service is attributed to faulty timing between service and ovulation in some cases. In others it may be due to either the ova being potentially unfertilizable or to the uterine and tubal environments being unsuitable for transport of sperm and fertilization. The latter view is favoured.17. When heat and ovulation occur as a result of PMS injection in the presence of a waning corpus luteum, normal service, sperm transport and fertilization occur.

Description: In the course of two breeding seasons 137 mature to aged ewes of mixed breeds but predominantly Border Leicester × Cheviots, Dorset × Cheviots, Suffolks and Hampshires and their crosses, have been injected with PMS or PU, and at different levels of dosage, and slaughtered at intervals after service to determine the sequence of events following treatment. In addition ten ewe lambs received similar treatment and eighty-one flock Suffolk and Romney Marsh ewes, of which forty-nine were injected, have been studied. The results may be summarized as follows:1. The injection of 500–2000 i.u. PMS on the 12th day of the oestrous cycle will regularly induce multiple ovulations at the ensuing heat.2. There is a significant dose-response relationship between 500 and 2000 i.u. PMS. Mean ovulation rates observed were: 500 i.u., 4·1; 1000 i.u., 10·6; 2000 i.u., 15·8. There is, however, considerable variation, the ranges being 2–9, 4–33 and 8–29 respectively.3. The injection of 1000 i.u. PU subcutaneously on the 12th day of the cycle causes marked ovarian and cyclic abnormalities, and heat may be entirely suppressed. When injected intravenously at heat following a priming injection with PMS on the 12th day there is no evidence that it increases the rate of ovulation; in other words, the ewe can ovulate up to at least thirty ova without difficulty, provided the follicles are matured.4. PMS levels of 500 and 1000 i.u. do not cause any apparent ovarian abnormalities apart from superovulation. A very high proportion of all follicles developed rupture and form apparently normal corpora lutea. PMS at 2000 i.u. causes lutein cysts and ovulation may be inhibited.5. PMS at 500 and 1000 i.u. causes no cyclic abnormalities, although cycle length is slightly shortened. In the event of the ewe failing to conceive, the subsequent oestrus is normal, and ovulation and fertilization of the ova occur.6. Commercial PMS is probably as effective as fresh PMS provided it is correctly standardized. There seems no reason to suspect differences in multiple ovulating efficiency between different batches of fresh PMS.7. While breed differences in response possibly exist they were not observed in these experiments. Nor were differences apparently related to the relative time of injection within the breeding season.8. There is an ovarian weight-PMS level, doseresponse relationship which is almost entirely accounted for by the numbers of corpora lutea and hence of luteal tissue.9. Multiple-ovulated ova are highly fertilizable. However, when fifteen or more are shed the rate of tubal transport is considerably accelerated and the proportion fertilized appears to fall. One- and two- cell ova have been recovered from the uterus within 48 hr. of service. Nine fertilized ova have been recovered from one ewe.10. Considerable embryonic mortality occurs before attachment of the blastocysts. None the less, multiple impregnation does occur but is followed by further early death. Up to thirteen attachments have been observed in one ewe, but all but three were showing signs of regression by the 19th day.11. Post-attachment mortality takes the form of an initial retardation commencing about the 15th day, embryos apparently dying a day or so later. The peak of mortality occurs between the 17th and 19th day, by which time definite signs of resorption are apparent.12. By 21 days equilibrium has been reached, the mean numbers of survivals of those ewes pregnant being some 260%. This level is maintained without further loss until the 68th day. Several cases of four normal foetuses were noted up to the 41st day, and one uterus containing six perfectly normal foetuses was recovered at 61 days.13. The overall fertility indicated by these slaughterhouse ewes varies with the level of PMS administered. While equilibrium is achieved by animals conceiving, at about 250–260% viable foetuses, regardless of the dose injected, there is increasing proportion of returns to service with increasing dosage. For the most part this appears due to hormonal imbalance at the time of ovulation and fertilization when an excessive number (〉 15) ova are shed. This results in accelerated ovum transport through the tubes and lowered rate of fertilization. Between ovulation rates of 4 and 12, produced by 500 i.u., rate of conception is extremely high. Of twenty-five ewes receiving 500 i.u. PMS, twenty-three (92%) conceived to the first fertile service. The conception rates were reduced to 80 and 60% by 1000 and 2000 i.u. respectively.14. Although after the end of the 3rd week there is no direct evidence of further foetal mortality, the percentage of lambs born in the flock ewes injected with 500 i.u. PMS was only 192% of those lambing or 167% of all ewes mated (147% for controls). This indicates a loss late in pregnancy. This can in part accounted for by abortion; one ewe aborted, due, is believed, to her carrying more lambs than she was physically capable of retaining.15. OffifteenflockSuffolksinjectedinthe 2nd year with 500 i.u. PMS, thirteen lambed, one aborted and one did not conceive. The thirteen ewes lambing presented twenty-five lambs, including one set triplets and one of quadruplets. All the latter were viable, but two sets of twins were bom dead. One triplet was lost on fostering and one other lamb was lost, so nineteen were tailed. Of fifteen controls, all lambed, giving twenty-one lambs bom of which twenty survived. Conception to first fertile service was higher in the injected than in the control ewes. In the preceding year when 1000 i.u. was given, both conception and lambing rates were appreciably lowered as compared with untreated controls. The significance of this in respect to the level of PMS administered is stressed.16. It is concluded that the major part of the embryonic loss is due to a uterine environment which is incapable of supporting more than a limited number of embryos. It is considered possible that there are breed differences in this, and that each breed, and individual within the breed, has ‘Maximum Potential Fertility’.17. This ‘Maximum Potential Fertility’ is not attained in normal breeding practice, since the number of ova shed by the ewe tends to constitute a limiting factor. Use of a level of PMS which will induce between three and ten ovulations—in the case of this experiment, 500 i.u.—removes this limiting factor, giving the individual full opportunity to express its full potential breeding capabilities.18. There is some indication that the use of PMS in lambs may not give good results, and its use for the while should be restricted to mature ewes.19. Since 500 i.u. PMS has resulted in a higher conception rate to first service and to a greater number of lambs born, it is apparent that this technique of injecting on the 12th day of the cycle a level of PMS which will result in a moderate number of ovulations is worthy of exhaustive field trials, notwithstanding the high post-natal mortality observed in the few cases which were allowed to go to term.20. In view of the higher indicated fertility of the slaughtered ewes which were mainly Border Leicester cross and Dorset × Cheviots—normally very highly fertile ewes as compared with the flock Suffolks—it is considered possible that this technique will yield best results with more highly fertile breeds.21. To have any hope for successful increase of fertility in mammals following gonadotrophin treatment the hormone must be administered at a time and at such a concentration that it will augment, but not upset, normal hypophysial and ovarian function.

Description: 1. If a crop varies in respect to a character which shows simple Mendelian inheritance then it is possible to estimate the proportion of cross-fertilization within the crop from the data obtained by (i) drawing plants from the crop and scoring them in respect of the character, then (ii) growing their separate progenies and scoring them.2. Maximum likelihood expressions are given for the estimation of p and f { = (1 — α)/(l + α)} from the genotypic classification of the parents and from the phenotypic classification of the progenies; where p is the gametic frequency of the dominant allel and α is the proportion of fertilizations in which the pollen is equally likely to come from any plant in the population.3. When the above expressions are applied to a case in winter beans, in which the parent plants were selected for high yield it is found that the different estimates of p agree, but those of f do not.

Description: Neglect of the oldest and most useful theory of scale models in geology. Its fundamental psychological value for a correct mental picture of the earth's larger aspects.The exact theory made more comprehensible. Its application in the domain of experimental tectonics improved upon.

Description: The ontogeny of Dalmanitina olini Temple (Upper Ordovician) is described on the basis of specimens from Scania and North Wales. The development is similar to that of D. socialis (Barrande), but good preservation has enabled some detailed changes in the cephalon to be followed. The protaspid and early post-protaspid stages bear an anterior pit in each axial furrow opposite the frontal lobe. The protaspid anterior glabellar furrow becomes joined to this pit by an oblique furrow, and forms with the latter a composite oblique furrow which develops into the adult anterior-glabellar furrow. This mode of development is considered probably to be common to all Phacopids: the significance of the anterior pits in this family is discussed. Preliminary observations are made on the growth-rates of various parts of the glabella, and the frontal lobe is found to grow in length (sag.) at a rate approximately equal to that of the rest of the glabella.

Description: Mr. Blundell's account of earlier work by A. F. Hallimond and J. T. Whetton (Bull. Geol. Surv. No. 2., pp 1–17, 1939) is inaccurate in certain particulars and is liable to mislead.

Description: The hypostome of a specimen of Encrinurus variolaris (Brongniart) from the Wenlock Limestone (Silurian) is described with particular reference to the intricate shape of the lateral wing. This lies very closely underneath the axial furrow of the cephalon in the region of the anterior pit, but it is unlikely that there was a direct articulation of the wing with the pit or the furrow during life.