摘要:

Preliminary observations on spiders' eyes showed that certain eyes fluoresce in ultraviolet light and others do not. The response of these eyes to ultraviolet and visible light has been investigated to discover the relationship, if any, of eye fluorescence with eye function.In the first part of this paper it is shown that of eight spiders from families with widely differing habits, vision and behaviour, five species reacted to light fluctuations and to differences in brightness of the primary colours blue, green and red. Three species did not respond to lightand only two,S. scenicusandE. falcata, indicated a preference for blue light. It was also found that the visual sensitivity ofS. secenicusextended into the ultraviolet. The second part of the paper gives the results of examination in ultraviolet light of the eyes of 40 species from 11 families. Spiders with poor sight and a preference for shade generally showed a strong fluorescence of all eyes. The anterior median and lateral eyes of those species with good sight fluoresced only weakly or not at all, whereas the posterior median and lateral eyes ofthese spiders fluoresced brightly.Freshly cut frozen sections of the eyes of two selected species,S. scenicuswith good sight andC. similiswith poor sight, were examined with the fluorescence, phase and polarizing microscopes. The localization of the fluorescence in these eyes is described and a fluorescent substance, common to all the spiders, was found in the lens of the eyes of most species examined.Additional information on the structure of the cornea and lens was also revealed by phase and polarized light microscopy.The results suggest that spiders' eyes respond to light in different ways and the fluorescent substance present in the lens of the eyes is related to eye function.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1967.tb02861.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

It is known from field observations that vernal gonad recrudescence begins in January for the Stock dove, a month later at the end of February for the Wood pigeon, while many town pigeons (Columba livia) have active gonads throughout the year.Photostimulation experiments demonstrate that spermatogenesis can be stimulated in the Stock dove by exposure to an artificial daylength regimeincreasing from 9.1 to 10.8 hours over 28 days. This photoperiod is the approximate equivalent of natural daylength changes occurring from late January onwards at 52° N. The same phototreatment, however, was not stimulatory for the testes of Wood pigeons, which required the equivalent of a March photoperiod. Natural daylength changes occurring in late November and December failed to evoke gametogenetic recovery in Stock dove controls.The gonads of feral pigeons in full breeding condition were unaffected when the subjects were transferred from full summer photoperiods to those found in midwinter and spermatogenesis was maintained in birds kept under winter daylengths for four months.The discussion mentions the problem of intraspecific geographical variation in photosensitivity. Scottish Wood pigeons begin their gonad recovery earlier and by March have considerably larger testes than birds in the south of England. Furthermore, they achieve this more advanced condition before the vernal equinox when daylengths are shorter in Scotland than in the south of England

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1967.tb02862.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

A male Wild goat,Capra aegagrusErxleben, 1777, is here described, which was obtained in Oman and is now in the gardens of the Zoological Society of London. It is the first known occurrence of the species in peninsular Arabia. The characters of the three species of subfam. Caprinae known to occur in the region are compared.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1967.tb02863.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Two new species of Ricinulei belonging to the genusCryptocellusare described from British Guiana. The habitat is described and figured and a method of keeping Rcinulei in captivity reported. Observations on feeding and mating are described and possible evolutionary implications of the mating behaviour are discussed

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1967.tb02864.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Photographs ofPterophyllumandGasterosteusfeeding indicate that they suck food into their mouths by expansion of the buccal and opercular cavities. The premaxillae are protruded as the mouth opens, and remain protruded as it closes. The mechanisms whereby these movements can be performed, by these and by more generalized acanthopterygians, are described. It is shown that the palatines of generalized acanthopterygians are so arranged as to prevent retraction of the premaxillae when the mouth is closed with the buccal cavity expanded.It is estimated, from rough measurements on a few species, that a teleost cannot suck into its mouth food that is further from its mouth opening than about one‐quarter of the length of its head. It is shown that protrusion of the premaxillae can be useful in getting the mouth opening close to food that is to be sucked in, expecially when it is to be taken from the bottom. The possible advantages of closing the mouth with the premaxillae protruded are discussed.The origin of the acanthopterygian protrusile mechanism is discusse

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1967.tb02865.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Computer methods are described for trend‐surface analysis of D'Arcy Thompson transformation grids, illustrated by data on skulls and jaws of hominoids.In comparing two diagrams the following steps are required. First, corresponding points on each diagram are marked, and their co‐ordinates are recorded. Second, the diagrams are scaled and fitted to give the best possible fit; this gives measures of size and shape difference. Third, the displacements of each point relative to its partner on the other diagram are subjected to trend‐surface analysis. The displacements are analysed in terms of linear, quadratic, cubic and higher order trends. Fourth, the differences based on the trends alone can now be estimated.The results on the illustrative examples are discussed, together with the difficulties in applying such methods. The nature of taxonomic (phenetic) affinity is also discussed, with suggestionsfor measuring different components of this concept.The techniques show promise for a wide variety of taxonomic and morphological applica

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1967.tb02866.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

The information at present available suggests that, when adult,Nucella lapillusmay prey upon a considerable number of different species, but that the diet of recently hatched dog‐whelks is rather more restricted. The food preferences of youngNucellahave been investigated and it has been concluded that, while the diet of young and adult animals may differ to some extent, it is probably equally varied at all ages, and that cannibalism may be a frequent occurrence amongst all age groups.It has been determined that the size of the prey influences the selective predation ofMytilusbyNucella.Dog‐whelks show a marked preference for mussels in the 1 to 3 cm size range which may possibly be identified chemotactica

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1967.tb02867.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

A detailed study on the structure of the gonad ofMonopterus albuswas made as a basis for analysis of gonadal steroids in this sex‐reversing teleost. Two types of males were identifiedand their existence appeared to be a result of the difference in gonadal ontogeny among the individuals in natural populations. The germinal area of the gonad, the gonadal lamellae, exhibited à zoned nature with regard to the location of the female and male germ cells. Observations suggested that the male germ cells originated from gonia pre‐existing in the inner zone of the gonadal lamellae before sex reversal. Natural reversal of sex in this protogynous hermaphrodite was found to be usually a postnuptial event and was always accompanied by loss of ovarian tissue and by development of interstitial (Leydig) cells. In the mesogonial region of the gonadal wall, peculiar mesenchyme cells were found, their significance remained uncer

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1967.tb02868.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Structural changes in the overies, uterus and vagina of the Senegal galago (Galago senegalensis senegalensis) have been observed at several stages of the oestrus cycle in both wild and captive animals. These changes have been correlated with the periodic opening and closing of the vaginal orifice and changes in vaginal cytology. The general pattern of these structural changes was similar to that seen in other mammals but showed the following special features: periodic opening and closing of the vaginal orifice; a prolonged post‐ovulatory invasion of the uterus and vagina by large numbers of eosinophil leucocytes; an unusually long life of the corpus luteum of the nonpregnant cycle. Although this animal did not menstruate its endometrium appeared to have to dual arterial supply like that seen in those higher primates that do menstruate. The coiled, elastic endometrial arteries formed a vascular adaptation to permit rapid dilatation of the uterus during early pregnancy. The urethra perforated the whole length of the long and peniform clitoris and this was associated with the periodic opening and closing of the vaginal orifice. These features made sexing very difficult. The observed time of occurrence of oestrus, together with field data on pregnancy stages and times of birth, indicated the probable occurrence of two breeding seasons in the year separated by long periods of anoestrus. Twinning was found to be uncommo

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1967.tb02869.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

The seasonal variation in percentage parasitization and in the average number of individuals ofEchinomeraspp. inLithobius forficatusandL. variegatusis described and discussed. It is suggested that infection byEchinomera hispidamay account for the low numbers ofL.forficatusin damp woodlands.Coccidia occur only inL. variegatusand the incidence of metazoan parasites is very low.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1967.tb02870.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY