摘要:

A detailed study of the hatchling musculature inSchistocerca gregaria(Forskål), and comparison with muscles of older first‐instar larvae and adults, revealed four categories of muscles: those which are present throughout life (permanent muscles), those which are present only in the hatchling and which break down during the first‐instar larval stage (first accessory muscles), those which are characteristic of larvae and break down in the adult (secondary accessory muscles), and those which are rudimentary or absent to start with, becoming functional in the adult. This last group, including the flight muscles and the muscles of the genitalia have not been studied. Of the remainder, the head and legs contain only permanent muscles, the contrast between larvae and adults being in the neck, thorax and abdomen. The positions and possible functions of the two groups of accessory muscles are discussed, particularly in relation to hatching, digging and ecdysis of the vermiform larva, and specific functions of the permanent muscles of neck, thorax and abdomen at this time are suggested, and compared with their better known functions in the fully hardened, free‐living insect.Summary:The study of the musculature of the newly hatched locust revealed not just the normal complement of muscles found in the adult, but batteries of accessory muscles which aid hatching, digging and ecdysial processes. Some of these muscles are attached across and onto the membranous regions and probably prevent ballooning of the intersegmental regions during high pressures, thus ensuring expansion of the presumptive sclerite regions rather than a separation of them.In the abdomen the lack of apodemes, the small overlap of adjacent sclerite regions and the easily distorted cuticle are all factors allowing the external muscles to assist the internal muscles and the accessory muscles in abdominal contraction. Such contractions are required for hatching and digging of the vermiform larva.Special muscles are associated with the ampullae and brustia, which break down during the first instar, while the other accessory muscles persist until the adult stage is reached, and are presumably used at later e

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1972.tb04081.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

A histological study of irradiated thyroid and pituitary glands of metamorphosingXenopustadpoles was made. Both glands shrink, reaching a minimum nine hours after irradiation and recover by 24 hours. It is suggested that sudden release of hormones may explain a reported hastening of metamorphosis in irradiated tadpoles.Summary:Xenopuslarvae received 2500 rads of whole body X‐rays.Nine hours after irradiation both pituitary and thyroid volumes were significantly less than the controls. From 24 hours after, the volumes had returned to control levels.The mitotic incidence in irradiated thyroids fell within five hours to one tenth of the control value and remained suppressed for at least three day

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1972.tb04082.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

The setal armature ofEurydice pulchraLeach is described using an ordinary optical microscope. On the basis of size, setae are divided into macrotrichs and microtrichs. Macrotrichs are further classified according to structural similarities into four groups. Only two types of microtrichs have been recognized. The distribution of the different setae on both adults and juveniles is described and where possible an attempt is made to relate morphology and distribution to function.Summary:The setal armature ofE. pulchrahas been divided into macrotrichs, varying in length from 0·025 to 0·4 mm, and microtrichs varying in length from 2 to 10 μm. The macrotrichs have been classified into groups based on structural similarities and 17 distinct types have been recognized. Each differ in length, degree of chitinization and modification of the shaft wall. The distribution of the macrotrichs has been described and particular types have been shown to occur in distinct positions on the body. Many of the macrotrichs are peculiar to one position on the body.Two types of microtrichs have been described, a single type approximately 10 μm in length and a smaller type 2 μm in length. The latter occurs in short crescentic rows principally on the pleopods and oostegites. All setal types occurring in the adult have been shown to be present in the newly emerged juvenile although the number developed is very much less. Similar setal types are present in males and females. An attempt has been made to relate the morphology and distribution of both macrotrichs and microtrichs to possible funct

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1972.tb04083.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Both sexes ofHaplodrassus umbratilis(L. Koch) are described and figured from material collected in the New Forest, Hampshire. Some comments on its habitat and phenology, and a list of other spiders found in the locality, are also given.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1972.tb04084.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

An account is given of the structure of the gaster and mechanism of the ovipositor in the females of the Eurytomidae. The histology and the possible functions of the components of the reproductive systems are described and its bearing on their phylogenetic relationships of the group discussed.Summary:The female gastral sclerites and ovipositor mechanism in the Eurytomidae have a number of distinctive characters. Within the family there is a progressive evolution of a coiling of the ovipositor associated with accommodating a longer shaft within the abdomen. Each ovary has three ovarioles and the shape of the egg is constant. There are two pairs of colleteral glands, a well developed “venom” system and a distinctive spermatheca.The family has affinities with the Torymidae and may be close to the ancestral chalcid st

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1972.tb04085.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Various aspects of territoriality were studied comparatively in a marked population of Reed and Sedge warblers at the Attenborough Nature Reserve, Nottinghamshire. Differences in arrival patterns, establishment of territory and particularly territory size were detected. In view of the dynamic nature of territory boundaries, a method is described for obtaining measures of mean territory size for comparative purposes. The sympatric species were largely separated by different breeding and feeding habitats, but there was also a degree of interspecific competition in some areas and interspecific territorialism was found to occur. Adults of both these migratory species were found to exhibit strong site fidelity, and there was some evidence to suggest that early post‐fledging experience may influence initial selection of a particular area and territory for first breeding.The adaptive significance of territory is discussed in relation to the findings presented and current hypotheses. There was some evidence which suggests that reduction of predation pressure and intraspecific interference through spacing out, as well as provision of a nest‐site may be important functions of territory in these species, but no evidence that food supply or population regulation are involved. The significance of interspecific territorialism is considered in relation to interspecific competition. The various factors effecting territory size and the patterns of nesting dispersion are also considered in an attempt to account for the striking interspecific differences found between these closely related species. It is concluded that although a multiplicity of factors may well be interacting in complex fashion, the more important of these stem from contrasts in the physical properties of the two habit

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1972.tb04086.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

In several field observations, foxes, Spotted hyaenas and other carnivores killed many more prey individuals than they could eat. Functional and causal aspects of this phenomenon are discussed and the conclusion is reached that these surplus kills are the consequence of behavioural compromises in both predator and prey to meet opposing environmental requirements.Summary:(1) Observations are reported in which carnivores killed considerably more prey animals than they could possibly eat, and causal and functional aspects of this behaviour are discussed. The species concerned were especially foxes and Spotted hyaenas, and references are quoted about surplus killing by other Canidae, Felidae and Ursidae.(2) It is argued that satiation in carnivores does not inhibit furthercatchingandkilling, but it probably does inhibitsearchingandhunting.Thus carnivores are able to procure an “easy prey” but normally satiation limits numbers killed.(3) Many, if not all, carnivores possess behaviour patterns which allow utilization of a kill at a later time, or allow other members of the same social unit or offspring to use the food.(4) Several prey species showed a lack of anti‐predator reaction under particular climatological circumstances; it is argued that this lack of response usually has survival value. Sometimes anti‐predator behaviour is accidentally made ineffective.(5) Surplus kills are made possible by (2) and (4) above, and only very rare circumstances give a predator access to so many prey that (3) is ineffective. It is suggested that surplus kills are the consequence of behavioural compromises in both predator and prey to meet opposing environmental requi

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1972.tb04087.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

As bat populations have been reported as decreasing in several countries and pesticides have been suggested as one of the main causes, a survey of the residue levels in bats from an East Anglian area was undertaken together with laboratory tests to evaluate the amounts found. The analytical results showed that bats are more heavily contaminated with residues of DDT‐type material than either insectivorous or carnivorous birds. Laboratory experiments confirmed that bats are more sensitive to DDT than other mammals and the rate of metabolism of pp'‐DDT to pp'‐DDE by Pipistrelles is slower than that of a passerine bird. Comparison of field and laboratory results shows that in the area studied during 1968 and 1969, bats were carrying one third of the lethal level of organochlorine insecticides as “background” residues with just under the lethal level after hibernation. This suggests that organochlorine insecticides could have caused population declines in bats in certain areas.Summary:Recently there have been reports of decreases in bat populations in several countries and pollution by insecticides has been put forward as one of the main causes. The present work was carried out to provide more information with regard to British bats by examining both the amounts of organochlorine insecticides carried in a locality in East Anglia and the lethal levels of the most common material, DDT, after poisoning by this substance. Examination of 30 bats of five species, mainly Pipistrelles from the area around Monks Wood, taken during the period April 1963 to October 1970, showed that 100% of the livers contained pp'‐DDE, 82% contained pp'‐DDT and 29% contained dieldrin. The mean levels of these materials in the liver was 10·68+4·62+0·29 ppm respectively. The most likely source of these residues is from the food supply of flying insects. It was found that the quantity of DDT material in the bat livers examined during the flying period was at a maximum in March after hibernation and lowest during November.Laboratory tests with Pipistrelles fed pp'‐DDT showed that they were more sensitive to DDT than any other mammals tested other than the American Big brown bat,Eptesicus fuscus.None died at less than 45 mg/kg, half between 45 and 90 mg/kg and mortality was complete above 90 mg/kg. Mortality started to occur when liver and whole body residues of DDT+DDE reached 43 and 45 ppm respectively though these amounts may be higher than normal due to the fatness of the laboratory bats used.The rate of metabolism of pp'‐DDT to pp'‐DDE was more slow in the Pipistrelle than in a passerine bird which explains the high occurrence and quantity of the parent compound in field bats compared to field bird specimens. The decrease in the quantity of DDT+DDE in bat livers from one end of the flying period to the other is mainly due to variation in the quantity of depot fat held in the body during these nine months. This is low in March and high in November.A comparison of field and laboratory results show that bats taken at random in the area studied were carrying a third of the lethal level of DDT+DDE during 1968 and 1969 with just under the lethal level being present after hibernation. Such high “background” levels infer that both the individuals and th

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1972.tb04088.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

The structures and physiology of the mammary glands of the lactating Red kangaroo are the most complex to be found in the class Mammalia. The female Red kangaroo can exhibit, simultaneously, two glands regressing from the tubular condition found at birth, one gland growing and differentiating from the tubular to an alveolar condition supporting a small pouch young, and a fourth in a state of full lactation supplying a young at heel. As lactation proceeds the two regressing glands become quiescent and then later re‐differentiate to the oestrus or birth condition independently of the lactating glands.As well as differing anatomically the two lactating glands are very different biochemically; the milk for the sustenance of the pouch young contains a large amount of palmitic and relatively little oleic acid whereas the gland supplying the young at heel secretes a milk with little palmitic and much oleic acid.Summary:The amount of crude lipid in the milk of the Red kangaroo sampled from day 1–4 day to day 360 of lactation tends to increase. The fatty acid complement of the milk fat taken day 1–4 to the 72nd day differed greatly from that taken at 100–360 days. The early milk triglycerides contained on the average 44·2% palmitic acid and 24·1% oleic, whereas in mature milks the proportions were reversed. Short chain fatty acids (C4‐C12) were virtually absent which was surprising to find in the milk fat of a herbivore. The Red kangaroo can elaborate simultaneously the two kinds of milk fat just described in two different glands supplying a small pouch young and a large young at heel respectively. It is suggested that early milks containing far more palmitic than oleic acid may only be found in mammals that have very special young such as the echidna, platypus and marsupials.The structure of the mammary gland from the condition found in the very young virgin doe to that of a doe suckling a 312‐day young is described. The Red kangaroo has four mammary glands one of which, suckling a small pouch young, differentiates and grows along with growth of the pouch young and produces milk with a high palmitic acid content, another, suckling a young at heel, has large fully differentiated and thin‐walled alveoli, while the other two (non‐suckled) show progressive regression from the condition at birth, followed by redifferentiation atc.128th day of lactation, both activities being independent of the activities of the

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1972.tb04089.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY