CURRENT LITERATURE 
BOOK REVIEWS 
The question of sex 
The determination and inheritance of sex have presented problems of peculiar 
interest and also of peculiar difficulty. CorRENS' has grappled with them from 
a new point of view and has gained some surprising results. His point of attack 
is through the hybridization of plants having different sex characteristics, a8 — 
for example the crossing of a dioecious species with a hermaphrodite or monoe- 
cious species. His most important conclusions are that each germ cell of the 
forms he has used carries a progamic sex tendency, but that the actual deter- 
mination of sex is syngamic, that is, it results from the chance that brings together 
two germ cells having particular sex tendencies. In Bryonia dioica he shows that 
the female germ cells carry always the same sex tendency, namely to produce 
females; while the male germ cells are of two kinds, half bearing the female 
tendency and half the male. The male tendency dominates over the female, = 
that when the eggs are fertilized by these two kinds of sperms, those which receive 
sperms bearing the female tendency produce females, and those which are fertil- 
ized by sperms bearing the male tendency produce males. ‘The females ar 
homozygous (2+) with respect to sex and the males are heterozygous (o+8): 
Evidence is presented that the same condition exists in Melandrium album, 2 
shown by crossing with Silene viscosa, and he considers it very probable that all 
dioecious plants are similarly constituted. The author is properly cautious 
discussing the applicability of these results to other classes of organisms thant 
with which he has dealt, and especially to animals, but he discusses Watson 
noteworthy studies upon the idiochromosomes of the Hemiptera,” and points Ha 
how readily these can be interpreted on the basis of’a sex relation similar t thai 
discovered in higher plants. 
epigamic modification of sex through the influence of nutrition oF Ks 
external conditions is not deemed to be wholly excluded, owing to the fact that iia 
sex may carry the other in a recessive or latent condition, and it is at least com 
ceivable that such latency may be to some extent modifiable by external ee 
In respect to the sex of hermaphrodite and monoecious plants, it is noted ted 
in all cases of “mosaic” inheritance which have been sufficiently invests 
Correns, C., Die Bestimmung und Vererbung des Geschlechtes nach 55508 
Versuchen mit héheren Pflanzen. pp. 81. figs. 9. 1907. Berlin: Gebriider — 
2 Witson, E. B., Studies on chromosomes. III. The sexual differences of cod 
chromosome groups in Hemiptera, with some considerations on the dete: tion 
inheritance of sex. Jour. Exp. Zool. 3:1. 1906. 
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