l6o H.H.Newman 



characters. The very tact that there is no sign of a paternal 

 influence should only serve to emphasize the importance of the 

 nucleus as a factor in determining the character of early develop- 

 ment. 



Bataillon,'' fertilizing the eggs of several species of Anura with 

 the sperm of the Urodele Triton, obtamed results very closely in 

 accord with those of Kupelwieser. There was no real nuclear 

 amphimixis, but the sperm nucleus remains in a mass and soon 

 degenerates. 



When individuals belonging to two genera of the same order 

 are crossed there is evidently less mcompatability, as a rule. 

 Herbst,^ for example, has made an extremely careful study of the 

 behavior of the paternal chromatin in the hybrids produced by 

 fertilizing the eggs ot Sphaerechinus with the sperm of Strongy- 

 locentrotus, in which he found that the male chromatin in some 

 cases divides more or less completely into chromosomes and takes 

 part in the mitosis of early cleavage, in others it seems refractory 

 and shows a tendency to go undivided to one motitic pole, and in 

 still others it becomes segregated into a small separate nucleus 

 in the 2-cell stage. Evidently at no period does the male chroma- 

 tin function normally. 



When two species belonging to the same genus are crossed there 

 is sometimes an approach toward complete compatability of the 

 nuclear materials of the two parents. In the two species of 

 Fundulus used m the above expernnents" we have a case in point. 

 Here there is no visible difference between the chromosomes of 

 the two species and the male chromosomes seem to behave quite 

 normally in cleavage from the first division onward. 



One would scarcely be justified, therefore, in drawing conclu- 

 sions concerning the normal process of heredity from data such as 

 have been described where there is every evidence that the pater- 

 nal contribution is either eliminated at a veryearly stage of develop- 

 ment or functions in a decidedly abnormal manner. 



Is there cytological justification for the statement that " tJie cJiar- 



^ Archiv. f. Entw. Mcch., vol. 28, pp. 43-48. 

 Archiv. f. Entw. Mech., vol. 27, pp. 266-308. 



