SEASONAL CHANGES IN THE MALLARD'S PENIS AND THEIR HORMONAL CONTROLHÖHN, E. O.
doi: 10.1111/j.1469-7998.1960.tb05599.xpmid: N/A
In adult wild mallards the penis weighs about 0·6 gms (0·05 per cent of body weight) for most of the year but increases to a weight of almost 3 gms. (0·3 per cent of body weight) at the height of the breeding season. In immature birds which had reached adult body weight the average penis weight was only 0·03 gms. (0·0026 per cent of body weight). The breeding season penile enlargement could be prevented by castration early in the spring. Evidence that Testosterone administration can cause enlargement of the penis in adult mallards was also obtained. Unilateral adrenalectomy did not effect penile or testicular weight.
COLLEMBOLA SYMPHYPLEONA FROM THE GAMBIA, WITH A NOTE ON THE BIOGEOGRAPHY OF SOME CHARACTERISTIC SAVANNA FORMSMURPHY, D. H.
doi: 10.1111/j.1469-7998.1960.tb05600.xpmid: N/A
Twenty species of Symphypleona are recorded from the Gambia of which twelve are new to science and are described. A brief survey is given of the chief vegetation and soil types to assist in classifying the habitat references in the text. Sminthurinus stenognathus Börner and Bourletiella spathacea Börner are noted as probably extending throughout the northern savanna belt of the Ethiopean region, having been recorded from both ends of this vegetation zone. Sminthurides cf. ramosus and Sminthurus macroceros Denis are recorded as occurring on both sides of the Atlantic and it is suggested that resistant stages which allow them to live under savanna conditions also fit them for long distance wind dispersal. In an appendix (vide infra) some information is given on some species of Sminthurides for comparison with species newly described here, and lectotypes are established for S. melanotus and S. spegazzinii from material in the British Museum collection.
THE DURATION OF PREGNANCY IN RHESUS MONKEYS MACACA MULATTAKROHN, P. L.
doi: 10.1111/j.1469-7998.1960.tb05601.xpmid: N/A
The gestation period has been estimated in 34 pregnancies which have occurred in the Birmingham colony of rhesus monkeys. The placental sign could be identified in 16 of them and the gestation periods in this group varied between the limits of 158 and 173 days. No placental sign could be recognized in the other 18 pregnancies and the records of menstrual bleeding could not be interpreted to give reasonably consistent estimates of the duration of pregnancy.
THE EVOLUTION OF THE PULMONATE GENITAL SYSTEMDUNCAN, C. J.
doi: 10.1111/j.1469-7998.1960.tb05602.xpmid: N/A
The evolution of the pulmonate genital system is traced from a prototype exemplified by the tectibranch Acteon. Many features remain almost unchanged in the genera studied, but there is a progressive degree of separation and specialization of the male and female ducts. Some genera of the Ellobiidae, such as Pythia, are undoubtedly primitive. However, it is suggested, following an investigation of the reproductive system of Chilina robustior, that the Chilinidae may stand closest to the ancestors of the Stylommatophora and the Hygrophila.
STUDIES OF THE HANDS OF LIVING PRIMATESNAPIER, J. R.
doi: 10.1111/j.1469-7998.1960.tb05606.xpmid: N/A
A study of passive movements and an analysis of the prehensile patterns of movement of the anthropoid ape hand was carried out in two young chimpanzees and one young orangutan, all approximately two years old at the time of study. The passive movements compare closely with those of a human child except in respect of the wrist and metacarpophalangeal joints of the fingers; in the case of the former joint, while flexion was very full, extension was limited. Passive movement of the metacarpo‐phalangeal joints was also very full, movement being limited only by contact of the fingers with the palm. A “double‐locking” mechanism of the 2–5th digits taking place at the metacarpo‐phalangeal joints is described. The anatomical basis of these movements and the “double‐locking” mechanism is discussed. Active movements were studied in terms of the prehensile patterns of the human hand (Napier, 1956) and it is shown that, while there is evidence of a functional duality of prehension in the hands of young anthropoid apes, the execution of the two grips differs profoundly from that of Man; the difference is discussed in terms of the disproportion in the length of the thumb and fingers in apes. It is suggested that the “double‐locking” mechanism of the fingers compensates in some measure for the ineffectiveness of the thumb in prehension.
EARLY PRONEPHRIC GROWTH IN NEOCERATODUS LARVAEFOX, H.
doi: 10.1111/j.1469-7998.1960.tb05607.xpmid: N/A
The pronephric systems of eight Neoceratodus larvae ranging from 11·5 to 16 mm. total length were analysed quantitatively and the measurements were treated statistically for two groups of mean total length 11·5 mm. and 15·3 mm. In the 15·3 mm. group the means of the measurements of the nuclear population, total volume of cells, overall pronephros volume and the internal surface area of the tubules show a significant superiority over the means of those in the 11·5 mm. group, but the mean of the glomus length is significantly lower. The individual cell volume which does not change significantly had a maximum range of 6500–6800 μ3. Quantitatively in terms of cell volume and qualitatively the pronephric systems of larvae of Neoceratodus, Anura and urodeles are similar, and have evolved in a parallel manner during phylogeny.