THE EFFECTS OF HYPERTOXIC SOLUTTOXS. 
473 
change. . . . The plasma membrane cannot undergo 
marked and prolonged increase of permeability without alte- 
ration in the nature and proportion of the cell-constituents ; 
this involves altered chemical organisation and eventual de- 
rangement of the cell-processes ” (pp. 344 and 345). 
It iSj therefore, a possibility that the hypertonic solutions 
of a fertilised egg exert a toxic action upon the nucleus 
by upsetting the normal relationship of the cytoplasm to 
electrolytic ions. 
Now, the permeability of the egg is changed when sperma- 
tozoon enters, and presumably the change is constant in degree 
for each species. When, however, the sperm of a foreign 
species is made to enter an egg, is it not possible that the 
change in permeability is not that which would have been 
caused by a sperm of the species to which the egg belongs ? 
If this be so, and the degree of change in permeability of an 
egg when fertilisated is, therefore, a function of the sperm, 
then the cytological behaviour of reciprocal crosses is 
explicable. 
Let the change in } 
permeability for ) 
E . a c u t u s eggs 
1 
fertilised 
hy 
E . a c u t u s sperm l)e P 
„ E. esciilentus 
Then „ E.esculentus 
and ., E.acutus 
E.esculentus „ Pj 
E. acixtixs is P 
E.esculentus is P, 
Let the difference between P and be about equal to the 
change of permeability in normally fertilised eggs of E. 
acutus which is brought about by the action of hypertonic 
solutions of appropriate strength. 
Now the chromatin of E. esculentus can withstand a 
change of permeability in the surrounding protoplasm equal 
to P — Pi without becoming abnormal,^ as is showm by its 
reaction to a hypertonic solution capable of producing such 
a change. Hence when the egg of E. esculentus is 
•' Presumably the change P— Pj is a little less than that caused iu 
eggs of E. esculentus hy .50 c.c. sea-water -|- 6 c.c. 2^ M. NaCl, as 
in the latter case one vesicle is produced, while in the hybrid E. 
acutus xE.esculentxis $ no such ahnorjnality occiu-s. 
