摘要:

The stomach of the hedgehog is a simple sac‐like structure, and is divisible into three main regions based upon the histological structure of the gastric glands.Peptic cells containing prominent Bowie positive granules are present at the bases of the rudimentary gastric glands at birth. A mucinogen component persists in these cells until about three weeks after birth.Oxyntic cells differentiate from a non‐mucoid cell type, they are far less numerous than petic cells throughout the suckling period.Pepsin assays on the fundic mucosa reveal that pepsin is present in considerable amounts at nine days of age, and that near‐adult levels are attained by about the end of the fourth week. Gastric pH declines during the suckling period, from near neutrality at birth to generally between 3.0 and 4.0 during the fourth and fifth weeks. Proteolytic digestion of antibody is delayed not through lack of enzyme but because the hydrogen ion concentration is generally inadequate for its action.Evidence is presented to support the suggestion that the cessation of antibody absorption in the hedgehog and the rat is brought about, initially at least, by changes in the secretory activity of the gut, rather than by changes in the absorptive intestinal epith

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1967.tb01642.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Of four species studied, tolerance of extreme temperatures in greatest inSpirorbis pagenstecheri(which extends highest on the shore) and least inS. corallinae(which always occurs immersed in water). The latter species breeds between May and August, the other three from May to October.S. borealisliberates its larvae mainly at the moon's quarters, but this fortnightly rhythm is less obvious inS. corallinaeand not found in the other two species.S. corallinaediffers fromS. borealisin being slower to re‐emerge after disturbance and in having a lesser breeding size, maximum size and life span. Growth in the laboratory is slower inS. tridentatusthan in the other species. Growth ofS. borealisunder natural conditions is much faster in summer than in winte

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1967.tb01643.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Sections of the adrenals of two male specimens ofLoxodonta africanawere examined. Apart from the dimensions of the gland and the amount and disposition of connective tissue in it, the most characteristic features were the very high lipid content of the cortical secretory cells, the large size of these cells, and the occurrence of dark cells in the zona fasciculata.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1967.tb01644.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Bilateral masseterectomy in newly‐born rats results in a diminution in cranial weight and size. Such reduction affects the facial skeleton to a greater overall extent than the braincase, although in each region it is the dimensions of length that are affected to a greater extent that are those of height or width. Such contrasts are not dependent upon changes in body weight.Removal of both temporal muscles—a smaller component of the masticatory musculature—results in little change in cranial proportions other than an increase in width of the braincase.Such findings can be related, first, to contrasts in the timing of growth in the braincase and facial skeleton and, second, to the extent to which muscular function is re

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1967.tb01645.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

A detailed description of the vertebral column, median fin skeleton and musculature is given. Comparisons based on the study of these structures inGagataandLoricariahave been made. It has been clearly demonstrated that these structures inSisorbear an unmistakable imprint of the bottom‐living habit of the fish and as such show a remarkable series of convergent modifications with the most highly specialized catfish family, Loricariidae, whileGagatashows an intermediate stage between the typical siluroid condition and the extreme type of modifications found inSisorandLoricaria.ThatSisordiverged early from the main stem of sisorid evolution is further supported by this stud

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1967.tb01646.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Measurements of four skull and five external characters were made on each of 277 specimens ofApodemus sylvaticus(L.) from the two Isles of Scilly (Tresco and St Mary's) on which it occurs and from six localities in mainland Cornwall. The skull characters were greatest length of skull, maxillary tooth row, cranial breadth and length of palatal foramen. Lengths of the pectoral stripe, tail, hindfoot and ear were obtained, as well as the weight of each animal. The age of each individual was assessed by means of a tooth wear character and a regression adjustment was used to bring all the characters to a uniform age class. The adjusted and unadjusted means have been calculated of each character for every locality. The sexes were separate throughout the analysis.The island mice are slightly larger than those from the mainland, the latter forming a fairly homogeneous group. In addition to overall size the most distinctive sign for the Tresco mice is the particularly small pectoral stripe. The St Mary's mice have a long tooth row, large pectoral stripe and large palatal foramen. The females were usually slightly smaller than the males.A canonical analysis was made in an attempt to account for as much variation as possible between groups using a limited number of linear combinations of the original measurements. The greater part of the variance was contained in the first two canonical variates. From these, the populations separated into three groups, i.e. the mainland group, the mice from Tresco and those from St Mary's. The two Scilly Island populations are as distinct from each other as they are from the mainland populations. Separate introductions from different sources and, possibly, slightly different genetic composition of the original immigrants may have accounted, in part, for the divergence shown by these two island stocks. It is not proposed that the island races should be given subspecific status.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1967.tb01647.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Island “races” of the field mouse (Apodemus sylvaticus) have often been used to support particular theories of colonization or microevolution. Comparisons betweenApodemusfrom a group of four islands in the Inner Hebrides (Rhum, Muck, Eigg and Canna) give support to the idea that the amimals were introduced onto these islands by man—mice first becoming established on Eigg and thence being transported to the other is

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1967.tb01648.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

The paper is one of a series of studies of the ontogeny of the innervation of the vertebrate limb in which the histogenesis of the nerves is correlated with the development of the pattern of behaviour in the limb. Here, the motility of the developing limb in tadpoles ofXenopus laevisis described, both in the normal larva and those in which the spinal cord is isolated from the brain. In spinal tadpoles the responses of the limb to electrical stimulation are correlated with its normal behaviour.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1967.tb01649.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

A catalogue of sounds from a laboratory population of Pigtailed macaques has been developed from spectograms. Sounds are divided into four general classes: clear, harsh and high‐pitched calls, and miscellaneous sounds. It appears that all parameters of the vocal signal are independently manipulatable. A plot of selected spectral characteristics demonstrated the uniqueness of individual signals. In some instances, different sounds are developed by rearrangement of specific fragments, or by acoustical activities performed on similar sounds. This latter phenomenon, which will be termedmosaicism, parallels aspects of language design. Lastly, comparison of spectrograms for Pigtailed macaques with those published for Rhesus macaques (Macaca mulatta) reveals similarities in structur

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1967.tb01650.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY