The determination of sex in animal develoi^ment. 747 



of the reduction. And in a valuable memoir ^) J. E. S. Moore has 

 arrived at Boveri's conclusion from researches on spermatogenesis. 

 Other zoological researches, such as those of Brauer and Meves, and 

 the whole of botanical opinion are in accord with this attitude. For 

 the particular epoch in question Moore has proposed the convenient 

 term "synapsis". 



Ou the last page of his memoir Moore writes: "Whatever the 

 synapsis may eventually turn out to be, it is evidently a cellular 

 metamorphosis of a profoundly fundaruental character, which would 

 appear to have been acquired before the animal and vegetable ancestry 

 went apart, and to have existed ever since." 



We have seen that, according to the testimony of Boveri, Brauer, 

 Moore, Guignard, Strasburger, Farmer, and others not named, in 

 the period of the history of the oocytes of the first generation, termed 

 by Moore the "synapsis", in some at present unknown way the re- 

 duction of chromosomes is brought to pass. This, though hardly 

 contradicted by Rückert, Haecker, Weismann and others, it is at- 

 tempted to explain away. To these authors the process here described 

 is not a real, is not the real reduction, and this they relegate to one 

 or other of the later divisions of the oo- or spermatogenesis. The 

 weight of actual fact, both zoological and botanical, seems to be against 

 the correctness of their views. There appears to be no doubt, that 

 in many of the best investigated cases, both in plants and animals, 

 the actual reduction is effected prior to the two divisions forming 

 gametes or spores. 



I have deliberately refrained from altering the earlier pages of 

 the present writing, in order to permit the reader to see how the 

 conclusion is finally arrived at, that the oocytes of the first generation 

 are concerned in the determination of sex. The last step may now 

 be taken. 



In the oocytes of the first generation, and (probably) in plants in 

 the spore-mother-cells, tvvo important phenomena come to pass. These 

 are the numerical reduction of chromosomes and the determination of 

 sex. Not merely an association, but a close and intimate connection 

 must subsist between the two ^). 



1) Moore, J. E. S., On the structural changes in the reproductive 

 cells during the spermatogenesis of Elasmobranchs, in : Quart. J. 

 microsc. Sc, V. 38, p. 275—313, 4 pi. 



2) Since the discovery of the reduction, there has been an ever 

 greater tendency — at any rate among zoologists — to connect it 



Zool. Jahrb. XVI. Abth. f. Morph. ^Q 



