摘要:

Summary.Trapping and routine examinations carried out in the Oxford district between February 1926 and August 1927, show that:1Sores arameusis found in a wide range of habitats, varying from pure grass‐land to dense conifer woods.2The breeding‐season is from May to August, and no pregnant females are found outside this period. It is uncertain whether the females have more than one litter during a breeding‐season.3It is suggested from the evidence available that neither male nor female shrews become sexually mature and breed during the year of their birth.4It appears that the young shrews reach a certain immature stage of growth by the late autumn of the year of their birth, and remain in that condition throughout the winter months. In the spring a marked increase in size takes place, and sexual maturity is re

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1931.tb06191.x

出版商:Blackwell Publishing Ltd    

年代:1931

数据来源: WILEY

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1931.tb06192.x

出版商:Blackwell Publishing Ltd    

年代:1931

数据来源: WILEY

摘要:

Summary.The foregoing discussion on this group of Palsoniscid derivatives reveals three main points:1That the two families owe their similarity to a Palsoniscid origin and to the limited nature of the evolutionary changes in which they have subsequently been involved.2In consideration of the distinct differences in the structure of the skull, the lack of intermediate forms, and their co‐existence side by side throughout Triassic time, it is probable that the two families arose from separate Palaoniscid stocks. Their many resemblances to the Palaeoniscids are genuine, and denote a true relationship.3The resemblances to the Semionotidae are, on the other hand, clearly due to convergence, for the structure of the head in Semionotids is much modified from that of these or any of the older groups. Stensio's suggestions that the Semionotidae may have been derived from the Catopterid‐Perleidid group is very highly improbable, for the Semionotids had already arisen as a separate Offshoot from the Palsoniscids in Mid‐Permian time, apparently long before either Catopterids or Perleidids had come into exis

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1931.tb06193.x

出版商:Blackwell Publishing Ltd    

年代:1931

数据来源: WILEY

摘要:

Summary.1The integument of the lac insect consists of an external layer of cuticle, underlying which there is the syncytial hypodermis, many of whose cells are modified into lac glands which secrete the resin of commerce.2The lac glands are of two types. The first type includes pleuricellular glands which are restricted in their distribution to the perivaginal pore clusters. To the second type belong unicellular glands with separate ducts and prominent nuclei. Some of these are very much limited in their distribution, being present only along six serpentine areas of marginal duct clusters. These are flask‐shaped in appearance, and have wide necks and prominent nuclei and nucleoli. Others belonging to the same category are distributed diffusedly all over under the integument, excepting the six serpentine areas, and possess a round fundus with filiform ducts.3The gut of the lac insect consists of a club‐shaped pharynx, an elongated œsophagus, a much‐convoluted ventriculus, a recurrent intestine, a colon with a cæcum, and, lastly, the rectum. A pair of salivary glands are also present.4The pharyngeal wall is made up of a single layer of columnar epithelial cells with prominent nuclei. The greater part of it lies within the chitinous framework of the mouth, and at its oral end are present a pair of salivary glands whose ducts open into it. The œsophagus is a long, narrow tube of the same histological composition as the pharynx, and is drawn in for some distance into the interior of the colon, where it forms the convoluted ventriculus. The wall of the ventriculus consists of a layer of large conical cells the free ends of which bulge out towards the lumen. At the base of these cells is a prominent deeply‐staining nucleus. This association of the ventriculus and the colon is a very interesting feature. The convolutions of the ventriculus are independent of the colon. The recurrent intestine may be said to consist of a proximal and a distal limb, the junction of the two being marked by the attachment of the Malpighian tubes. The wall of the intestine is thrown into folds, and the lumen is lined with a layer of chitinous intima. The wall of the colon consists of a layer of moderately elevated conical cells. The cellular nature of the wall of the colon is suppressed in the zone enclosing the convolutions of the crop. The rectum has a very thin wall. A few prominences in its wall are the only indication of its cellular character. The lumen of the rectum is lined by a chitinous intima which shows a few ridges. The Malpighian tubes, of which there is a pair, present a beaded appearance due to the distention of their cells with excretory matter. They are made up of two alternating rows of cells.5In common with most other Coccids, the female lac insect also produces large quantities of “honeydew,” which is sought for by the ants. The belief that honeydew is secreted for the ants, and that the ants, in return, are of service to the lac insect in warding off their enemies, does not seem to rest on any positive evidence. This question has been discussed thoroughly in the preceding pages, and it has been shown that the honeydew is dependent upon a vital process for its production, and is not produced for the ants or, for the matter of that, for my other insect. Arguments have been brought forward negativing the belief in the symbiotic relationship between ants and the female lac insect. The prevalent belief that ants are injurious to a successful cultivation of lac has been shown to be without foundation.6The author has shown that the dorsal spine is not capable of discharging any of the functions hitherto assigned to it by various authors. At the same time it is difficult to imagine what function it could possibly discharge in the female lac insect.7The female lac insect possesses two pairs of spiracular openings. The anterior pair of spiracular openings is borne by the brachia, which are grooved on their outer margins to lodge the spiracular openings of the respective sides. Each spiracular opening leads into the caværa, from the base of which the main tracheal trunk arises, which, by further subdivisions, gives rise to a bushy tuft of trachea. The caværa is bounded by the peritreme, which bears numerous pores. The posterior spiracles are situated near the oral end of the insect, and, though built on the same plan, are smaller in size and lack muscular slips. There are trachea in association with these also.8Through the dimples of the brachial plates and the anacerores of the anal tubercle waxy threads are given off. It has been shown that these are not the attenuated extremities of the tracheæ, being formed by wax glands situated under the areas referred to, and hence of a waxy character. The structure of the wax glands has been dealt with, and they have been shown to resemble the wax glands ofPseudococcusandCeroplastesin many respects.9There are three bundles of muscles. Two of these are attached near the mouth‐parts on the one hand, and, on the other, are inserted in the interspaces between the anal tubercle and the brachia of the corresponding sides. The third bundle is inserted at the oral end near the æsophagus, on the one hand, and, on the other, extends into the anal tubercle, which it muscularizes. The correct morphological value of these muscular bundles has been indicated in the text.10No vascular vessel or pulsatile vessel was detected in the female lac insect.11The nervous system is represented by two separate ganglia, one of which is situated close to the colon‐cum‐rectum portion of the gut; the other lies close to the Malpighian tubes. The first of these represents the thoracico abdominal ganglion of the larva, whilst the other is the cerebral ganglion. The thoracico‐abdominal ganglion gives off a few nerves which innervate the interior of the insect.12The ovary of the female lac insect is an arboreal organ bearing numerous diverticula in which the embryos subsequently undergo development. The oviducts of opposite sides unite to form the uterus, which leads into the vagina. The female genital opening is situated on the anal tubercle. The receptaculum seminis consists of a stalk and a terminal chamber, and is attached to the oviducts just a little above the point where the two meet.13The wall of the ovary consists of a thin cellular layer. The oviducts have the same essential structure as the ovarian wall. The wall of the uterus consists of an internal layer of columnar epithelium resting externally on a layer of circular muscles external to which are the longitudinal muscle fibres. The vagina has the same structure as the uterus, but differs from it in having the cells of the epithelial layer more elongated and closely packed up on account of its being thrown into folds and in having the lumen lined by a chitinous intima. The receptaculum seminis has the same histological structure as the uterus, but no cell boundaries are distinguishable in its internal epithelial layer.14The oviducts open to the exterior quite independently of the rectum on one side of the anal tubercle.15The larvæ emerge through the female genital opening and not through the anus, spiracle, or by the rupture of the skin as described by many previous workers.16The death of the female lac insect seems to be due to the incapacity of the Malpighian tubes to store up any further quantity of waste matter when its cells, in the advanced stage of life, have become distended to the utmost. The Malpighian tubes, from larva onwards, gradually become laden with waste matter until they become distended to the utmost, when death, due to autointoxication, results. Similar instances in the Animal Kingdom are provided by th

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1931.tb06194.x

出版商:Blackwell Publishing Ltd    

年代:1931

数据来源: WILEY

摘要:

Summary.1During March, April, and May of 1930 observations were made in South Africa on the Chacma Baboon (Papio porcarius).2Baboon packs, in which were nursing females as well as females with sexual skin swelling, were seen in the Eastern and Western Provinces.3On May 4th twelve females belonging to the same pack were killed near Grahamstown, in the Eastern Province. Four were non‐pregnant: one of these was menstruating, one was in the pre‐ovulation, and two in the post‐ovulation phase of the cycle. Five were pregnant: the first of these had an embryo 2·5 mm. in length, the second one of 16·5 mm., the third one of 19 mm., the fourth one of 65 mm., and the fifth an apparently full‐term male fœtus with a crown‐rump length of 230 mm. Three were lactating, and their babies were caught alive.4Data are provided regarding the times of milk‐tooth eruption in baboons, indicating that two of the babies were about two months old and the third about four months.5A complete reproductive cycle in the baboon—the shortest interval of time between two births by the same female—is approximately a year. The females shot on May 4th were representative of practically all stages of the cycle.6This proves that the Chacma Baboon has no demarcated breeding season, but that it can give birth at any time of the year.7The question of the breeding of other Old World primates is discussed. Records of monkey births in captivity indicate that most Old World primates can conceive at any time.8The possibility that there exists a seasonal variation in the monkey's conceptility rate does not conflict with the underlying fact that, the baboon, and probably most other Old World primates, has no demarcated breeding‐season. There is a fundamental distinction between mammals with a fixed anœstrus, like the ferret, and mammals like the baboon

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1931.tb06195.x

出版商:Blackwell Publishing Ltd    

年代:1931

数据来源: WILEY

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1931.tb06196.x

出版商:Blackwell Publishing Ltd    

年代:1931

数据来源: WILEY

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1931.tb06197.x

出版商:Blackwell Publishing Ltd    

年代:1931

数据来源: WILEY