May 27, 1898.] 



SCIENCE. 



737 



more or less effectual influence upon them, 

 in order to extract from them the best pos- 

 sible results. His essay falls into three 

 parts — a summary of the writings of his 

 predecessors, an account of his own re- 

 searches and deductions, and finally a de- 

 scription of the method of treatment he 

 has devised, with illustrative cases. 



In the development of an embryo the 

 generative organs are at first indifferent — 

 hermaphrodite; in the further process of 

 growth one set develops while the other 

 atrophies. This tendency must be prede- 

 termined from the time of fertilization, for 

 each cell formed from the ovum must have 

 sexual characters, since these are not 

 confined to the generative organs, but ap- 

 pertain to the whole body. The readiness 

 with which an ovum can be fertilized de- 

 pends upon its position in the ovary, the 

 thickness of its envelope, etc., and these 

 may also have a bearing on the question of 

 sex. In other words, the predetermination 

 may precede fertilization, and of this con- 

 firmation is found in the development of 

 bees and in the production of male and fe- 

 male flowers by plants under different nu- 

 tritive conditions. In this connection Pro- 

 fessor Schenck enunciates and discusses at 

 considerable length the views of previous 

 writers. He points out that the male sex 

 preponderates to a definite though slight 

 degree in the total number of births, and 

 that the sex of a child is more likely to be 

 that of its older parent. He pays particu- 

 lar attention to the theory of crossed sex- 

 ual heredity, by which each sex tends to 

 propagate the other. Thus if the sexual 

 power of the male be greater a female off- 

 spring is more likely to result, and vice versa. 

 This theory is threshed out most thoroughly 

 and with abundance of quotations and ex- 

 amples ; in the end Professor Schenck prac- 

 tically accepts it, and makes use of it in his 

 further work. With regard to the influence 

 of environment upon sex, he quotes Robin's 



statement that in warm climates females 

 preponderate, in cold and unfavorable, 

 males. Born also showed that 95 per cent, 

 of artificially fertilized frog's eggs hatched 

 out as females, this being an eifect of nutri- 

 tive conditions acting after fertilization. 

 Thury's researches are fully analyzed, and 

 are stated to have originally called Profes- 

 sor Schenck' s attention to the subject. 

 Thury found that cattle fertilized at the be- 

 ginning of ' heat ' threw more females, at 

 the end more males. This he explained by 

 the degree of ripeness of the ovum, but 

 Professor Schenck accounts for it on the 

 crossed inheritance theory, the sexual power 

 of the female being at its greatest at the 

 end of the period of rut. This part of the 

 work is summed up in the statement that 

 the sex of offspring largely depends upon 

 the state of nutrition of the parents, par- 

 ticularly that of the mother during preg- 

 nancy. During this period the difierence 

 between intake and excretion represents the 

 food of the embryo, and hence requires 

 special attention. The temperature is 

 slightly raised owing to oxidation processes, 

 which entail a considerable consumption of 

 red blood corpuscles and consequent dimin- 

 uation of htemoglobin. 



The second section begins with the enunci- 

 ation of the fact observed in domestic animals 

 and in insects that the better the mother is 

 nourished the more females she produces, 

 the number of males remaining practically 

 constant. This influence upon the fcetus 

 in utero has received but little attention 

 from the practical point of view, and Pro- 

 fessor Schenck consequently set out upon a 

 series of observations based on the theory 

 of crossed sexual inheritance. He first in- 

 vestigated the excreta, and particularly the 

 carbohydrates of the urine. The presence 

 of a certain amount of sugar, which is com- 

 monly recognizable by the phenyl-hydrazine 

 test in perfectly normal individuals, indi- 

 cates incompleteness of the oxidation pro- 



