226 EDITH PINNEY 



late cleavage stages, no attempt was made to explain the de- 

 velopmental abnormalities in the hybrids on the basis of the 

 behavior of the chromatin. 



The first attempt at such an analytical comparison of develop- 

 mental and cytological processes is that of Glinther and Paula 

 Hertwig, whose results were published in February, 1914. These 

 investigators made, among many other teleost crosses, six that 

 were heterogeneous. The results of all of their experiments, 

 although extremely diverse, are thought by them to be due pri- 

 marily to a disharmony of idioplasms as set forth by 0. Hertwig: 

 ^'Die idioplasmatische Disharmonie beruht auf der verschiedenen 

 materiellen Beschaffenheit der miitterlichen und vaterlichen 

 Kernsubstanzen und ist von dem Grade der Verwandtschaft 

 zwischen den beiden zum Bastard verbundenen Stammformen 

 abhangig." They recognize that this alone cannot explain the 

 unequal success of reciprocal crosses. They therefore assume a 

 further disharmony between the cytoplasm of the egg and idio- 

 plasm of the spermatozoon, a relation which is not necessarily 

 the same in reciprocal hybrids. Although the mam conclusion of 

 their work is that the disturbances in development are due to 

 the combined effects of disharmonies, first, between the nuclear 

 constituents of egg and spermatozoon, and, second, between the 

 cytoplasm of the egg and the spermatozoon, nothing abnormal 

 was found in the behavior of the nuclear substance until very 

 late embryonic stages when the nuclei are said to be abnormally 

 large. They did, however, obtain some evidence of a specific 

 effect of the cytoplasm. 



The observations of Miss Morris ('14), on the cross Fundulus 

 heteroclitus 9 X Ctenolabrus adspersus d' are especially inter- 

 estmg in this connection, since this is a cross which gives 

 purely maternal larvae. Miss Morris found two types of chro- 

 mosomes in the early cleavage stages of the hybrids which she 

 identifies as the two paternal types. The slight lagging of the 

 foreign chromatin does not, she thinks, result in any elimination 

 of chromosomes and all of the maternal and paternal chromatin 

 participates in mitosis. She rejects Loeb's theory ('12 a), 

 ''That the function of the sperm in such hybrids is merely that 

 of a parthenogenetic agent," and concludes that the Fundulus 



