8 The Ohio Journal of Science [Vol. XVII, No. 1, 



maternal chromosomes, the eggs containing this cytoplasm were 

 alike in the length and uniformity of the time of development, 

 and in the total number hatching. 



Whether the matrocline hybrids of echinoderms, so far 

 observed only as larvae, would on becoming adults show any 

 less the characters of the mother than in the developmental 

 stages, can only be conjectured. But the demonstration of 

 such a change between embryonic and adult life in the rotifers 

 supports Conklin's suggestion that it is the larval characters 

 which, in animals in general, are influenced by the egg cyto- 

 plasm. When, however, in writing of the function of the 

 chromosomes, Conklin states that they have only to do with 

 the details of adult structure, I am unable to follow him. Nor, 

 it seems to me, are some of the larval features which are condi- 

 tioned by the cytoplasm, for example, the form of the larval 

 skeleton of echinoderms, to be regarded as anything else than 

 details. Geneticists, it is true, usually deal only with details; 

 but that is because no mutations which involve radical changes 

 in fundamental processes, and still leave the organisms capable 

 of breeding with the parent form, have occurred. It seems 

 much more probable that even the fundamental features of the 

 adult are products of chromosome determination. 



Cytoplasmic influence in heredity may appeal more to a 

 certain type of mind if there is a mechanism through which it 

 operates. That type of mind (or some other) has already found 

 the mechanism. Hereditary importance is attributed by some to 

 those bodies, found in the cytoplasm of many cells, called 

 chondriosomes. One of the leading cytologists of America 

 (who be it said is an ardent advocate of the chromosome 

 hypothesis) admits that "probably" the chondriosomes have 

 something to do with heredity. But I suspect that his admis- 

 sion was made chiefly to clear his conscience of any bias in the 

 opposite direction. The only evidence that chondriosomes play 

 any role in heredity seems to be that the cytoplasm plays such 

 a role — and the chondriosomes are in the cytoplasm. 



Zoological Laboratory, University of Michigan. 



