Coordinated development in the fly foot: Sequential cuticle secretion

Development of the adult fly foot falls into clearly defined phases of cell division, growth, cuticle secretion and cell death. The pulvillus is composed dorsally of two giant cells and ventrally of thousands of minute tenent cells; the former produce the dorsal footpad cuticle and the latter the thousands of tenent hairs. Cell divisions are still occurring in future tenent cells when increase in size of the cells and in polyteny of the chromosomes is already occurring in the two dorsal cells. Also cell death occurs considerably earlier in the tenent cells, yet the sequential secretion of some six cuticular layers takes place at comparable times in dorsal and ventral cuticles. The cuticular layers formed are, in their order of secretion: ecdysial membrane, cuticulin of the epicuticle, dense exocuticle, homogeneous exocuticle, an intermediate layer, wax of the epicuticle, and an extensive mass of endocuticle. The ecdysial membrane seems to perform an important mechanical role in maintaining the shape of the delicate cytoplasmic projections of the tenent cells, before and during cuticle secretion, and in establishing the cuticular pattern of ridges in the dorsal cuticle. Comparisons are made with trichogen cell cuticle development and with tracheal cuticle. Tracheal, trichogen and dorsal footpad cuticle patterns are compared. Details of giant cell activity provide a working basis for studies of nuclear-cytoplasmic interactions, and the whole system raises many unsolved problems in the general field of cell differentiation and pattern formation.     

Preliminary observations on the role of Acacia gum chemistry in Acacia utilization by Galago senegalensis in Kenya

A census and preliminary observations on the ranging and feeding behavior of Galago senegalensis were made in a savannah-woodland site in Kenya. Population densities in three slightly different habitats were all approximately 1.5 animals/ha. Ranging patterns suggested the existence of territorial behavior. The diet of the galagos was exclusively insects and gums of two species of Acacia. The gum of A. drepanolobium appeared to be preferred to that of A. xanthophloea. The chemistry of the gums suggests that this preference is not due simply to the total level of phenolics or to avoidance of condensed tannins but may relate to the presence of compounds (e. g., flavonoids) having nutritional or hormonelike action.     

Pregnancy outcome in free-ranging vervet monkeys (Cercopithecus aethiops)

A preliminary assessment of individual female differences in conception rate and fetal wastage has been determined for a population of wild vervet monkeys (Cercopithecus aethiops). One of three troops of vervet monkeys, the subjects of a long-term behavioral study, was trapped and blood was obtained for electrophoretic analysis. Pregnant females exhibited a distinctive serum aminopeptidase phenotype allowing a conclusive determination of pregnancy. Of the seven females diagnosed as pregnant, three later gave birth. Of the females that aborted, two were nulliparous and one was very old. Studies of captive animals have indicated that age and rank may affect a female's ability to carry a fetus to term. These factors, rather than the trapping procedure, may have been responsible for most of the fetal loss in the trapped troop. A comparison of all three troops for a 3-year period indicated that there were fluctuations in yearly birth success of individual females, as well as a relatively high miscarriage rate. The results of this study indicate the advantages of obtaining joint behavioral and biological data.