6 Mr Gray, The Effect of Hypertomc Solutions, ete. 
suggests, the male chromatin goes wrong because it is “out of 
tune” with the female cytoplasm, why are not both reciprocal 
crosses abnormal? And in the case of ZL. acutus x E. esculentus 
we should expect the more sensitive #. acutus chromatin to go 
wrong when it enters the cytoplasm of the more resistent H. escu- 
lentus, and this is not the case. 
The proof of the hypothesis here put forward would be in the 
demonstration of the fact that the permeability change of an egg 
when fertilised differs according to the species of sperm used, in 
other words, the degree of permeability change should be a function 
of the sperm*®, 
A more detailed account of this work will appear in the forth- 
coming number of the Quarterly Journal of Microscopical Science 
(Vol. LvuI.), where references will be found to all the works quoted 
in this paper. 
* As in some cases of hybridisation there is no doubt whatever that it is the 
male chromatin that becomes abnormal it is obvious that changes of permeability of 
the cytoplasm, such as can be induced by the sperm, cannot be a sufficient explana- 
tion of all the abnormalities observed in cross-fertilised eggs. 
