DEVELOPMENT OF EYE COLORS IN DROSOPHILA: NATURE OF THE DIFFUSIBLE SUBSTANCES; EFFECTS OF YEAST, PEPTONES AND STARVATION ON THEIR PRODUCTION

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Abstract
An account of chemical investigations of the nature of the v+ and cn+ hormones of Drosophila is given. It is concluded that they probably belong to the group of amino-bases. It is shown that the effects of Colliphora extracts, containing these hormones, are proportional to the concentration. It is shown that under the influence of starvation v flies undergo a modification of the eye color, similar to that produced by the v+ hormone. It is shown that similar effects are produced by feeding Drosophila larvae on small doses of dry yeast. At low doses the effects produced are proportional to the concentration of yeast. Higher doses of dry yeast suppress the effect which is also suppressed by the presence of glucose in the medium. Various peptones also produce a hormone-like effect when fed to v larvae. Again the effect is proportional to the concentration of peptone at low concentrations, and decreases above a certain maximum. High concentrations of yeast extract suppress the effects of the peptones, but not the effect of Calliphora extracts. The relations of the age of the larvae to the intensity of the effects produced by yeast extract and by peptone are studied. Gelatin peptone does not produce an effect comparable to that of the other peptones tested, but does if tryptophane is added. Neither starvation, nor dry yeast, nor peptones, produce the modification of the eye color of cn flies. Neither dry yeast, nor peptones produce effects on v flies when injected into the body cavity of the larvae. An attempt is made to interpret all the effects observed by a single hypothesis.