200 KANSAS UNIVERSITY SCIENCE BULLETIN. 



It is with no desire to magnify my own humble part in the 

 attack upon these problems that I make mention of the manner 

 in which they have presented themselves to me. I have thought 

 that by means of a concrete example I might perhaps more 

 clearly exhibit the grounds for my theoretical beliefs and the 

 reasons for the faith that is within me. I shall therefore first 

 indicate the main features of parallelism between germ-cell 

 structure and taxonomic relations that have appeared from 

 investigations upon certain orthopteran species and then at- 

 tempt explanations of the causal connections between the two 

 sets of phenomena in the light of our present general knowl- 

 edge. 



From the study of a large number of saltatorial orthopteran 

 species it appeared that the normal numbers of chromosomes 

 in the males fell, in general, into two groups of twenty-three 

 and thirty-three respectively. To a cytologist this was a very 

 suggestive fact, for it indicated a precision in the organization 

 of cells that was in advance of anything that had before been 

 imagined. It was doubly interesting to note the opinions of 

 orthopteran taxonomists with regard to the relationships of 

 these species and to discover that they had segregated them 

 into definite corresponding groups which are called "families." 

 Merely as the result of the study I had made of the germ-cells, 

 I would have classified these insects into two groups, one hav- 

 ing a complex of twenty-three chromosomes and the other of 

 thirty-three. On the other hand, many taxonomists, from care- 

 ful and minute examination of the external anatomy of these 

 same species, had agreed in placing them into family groups, 

 which they call the '' Acrididse" and "Locustidm." Now, these 

 families are clearly distinguished apart by ordinary taxonomic 

 features, and to speak of the "short-horned" and "long-horned" 

 grasshoppers is to summon before the mind of one acquainted 

 with the animals very definite types of structure. And yet the • 

 distinction between these insect families is no more apparent 

 to me from an inspection of the gross anatomy than it is from 

 a study of the germ-cells. The possession of a complex of 

 twenty-three chromosomes is just as typical an acridian char- 

 acter as is that of short antennae. I do not regard it any argu- 

 ment against this cytological means of discrimination to learn 

 that other than acridian organisms have twenty-three chromo- 

 somes, for so do other animals have short antennse. 



Clearly enough, it would seem, we have here an indication of 



