ORIGIN OF SEX. This is an unsettled problem. We do not understand how•, from being at first hermaphroditic or asexual, as was probably the ease, the male and female characteristics became gradually established. What in the higher ani mals determines sex is also an unsolved problem. Hundreds of theories have been proposed as to the epoch at which the sex of the embryo is finally determined. Food or nutrition is as im portant a factor as any in determining what the sex of the future animal may be. Certain ex periments throw light on the subject in the case of animals. Yung divided a batch of tadpoles into three lots, the proportion being 54.46, 61.39, and 56.44. The average number of females was thus about 57 in 100. In the first brood by feeding one set with beef be raised the per centage of females from 54 to 78; in the second lot, fed with fish, the percentage rose from to 81; while in third lot, when the especially nutritious food of frogs was supplied, the per centage rose from 56 to 92; thus in the last case the result of high feeding was that there were 92 females to 8 males. In the honey bee the queens
are fed with richer, more nitrogenous food than the workers; hence in the latter the ovaries are undeveloped; it is so with the white ants and ants. In the wasps when both males and females arise from fertilized eggs. Siebold's observations tend to show that predominance of females is due to better nutrition. Giron divided a flock of 300 ewes into equal parts, of which one-half were extremely well fed and served by two young rams, while those of the other half were served by two mature rains and kept poorly fed. The propor tion of ewe lambs was 6Q per cent. and 40 per cent. Dusing's experiments leave little doubt that abundant moisture and food tend to produce females, while high temperature produces males; lie found that the heavier, well-fed ewes produced ewes, while the lighter, under-fed ewes brought forth males.