DEPARTMENT OF EXPERIMENTAL EVOLUTION. 99 



a difference exists in vegetative luxuriance between the two sexes in 

 these forms it is always the female ( 9 ) that is the more luxuriant. 



The general results of the foregoing investigation were presented 

 in a paper read by Dr. Blakeslee at the Cleveland meeting of the 

 American Association for the Advancement of Science and are sum- 

 marized in the issue of Science for June 6 by Dr. Blakeslee. The 

 detailed results are to be incorporated in a paper now in preparation 

 on "Sexual reactions between unlike species." 



The argument in the foregoing publications is based upon the 

 sexual character of unequal gametes in heterogamic hermaphroditic 

 species. Since the sexual nature of these gametes has been recently 

 called in question by Gruber and Atkinson, Dr. Blakeslee found it 

 necessary to make a careful study of all the heterogamic forms avail- 

 able, following the process of sexual reproduction in living material — 

 a procedure that apparently has not been satisfactorily attempted 

 before. The results are given in a paper by Dr. Blakeslee published 

 in the April issue of the Mycologisches Centralblatt and seem amply 

 to warrant the line of argument already mentioned. 



Dr. Blakeslee had previously shown that if a given dioecious species 

 (Mucor V) be taken as a standard, its male (d^) race will show a 

 sexual reaction with the female ( 9 ) races of all the other dioecious 

 forms under cultivation, but not with the other male (cf) races. 

 Conversely, its female ( 9 ) race shows a sexual reaction with male 

 (cT) races only. The conclusion seems unavoidable that all the 

 female ( 9 ) races have something in common which elicits a similar 

 response from the male ( cf ) race of Mucor V and vice versa. That 

 this common element is of a chemical nature and therefore demands 

 a chemical study is a natural inference. There are no other forms 

 known that seem to offer a suitable subject for such a chemical 

 investigation. Other available organisms in which there are sepa- 

 rate male {d') and female ( 9 ) individuals show a sexual division of 

 labor in that the female ( 9 ) has the feeding function predominatingly 

 developed, either furnishing food to the egg or to the developing 

 offspring. Any chemical differences, therefore, between male (cf) 

 and female ( 9 ) individuals or between sex-cells found in these forms 

 would have no necessary connection with the sex differences, but 

 rather would be connected with the one-sided nutritional function 

 of the female ( 9 ) sex. In the mucors, however, the sex-cells are 

 morphologically equivalent and the male and female plants take an 

 equal share in feeding the developing offspring. 



Chemical Differences between the Sexes, by A. F. Blakeslee and R.A.Gortner, 



Starting with the hypothesis that sex difference might be a 

 difference in the proteins of the two sexes, a beginning was made with 

 the blood tests for protei»s. As yet work has been done only with 



