m'clung: cytology and taxonomy. 201 



the great precision in organization so long inferred for the 

 germ-cells. Were our knov/ledge more extensive we should 

 doubtless see yet further evidences of this — and certainly it is 

 our duty to seek them out — but for the present we must make 

 use of this suggestive fact and learn from it what we may. The 

 most important conclusion that can be drawn is that these 

 chromosomes are primary factors in the mechanism of devel- 

 opment, for no other structures of the cell exhibit any such 

 constancy and definiteness of organization to parallel the 

 structural differences of the resulting animals. Since they 

 occur in the same number throughout the family, and since 

 the end result of their changes is essentially the same in every 

 case, they must be individually alike in each complex. Further, 

 it may be concluded that always their functions for any given 

 period in ontogenesis are the same. With this as a beginning 

 it becomes a reasonable hope that we may attempt an analysis 

 of the processes of organic development by associating modifi- 

 cations of the acridian type of body with variations in the 

 chromosome complex of their germ-cells. In other words, the 

 task of the cytologist engaged in the study of this group is to 

 learn the history of the individual chromosomes and to associ- 

 ate this knowledge with what is known regarding the develop- 

 ment of somatic structures. 



This is obviously no light task, but, on the other hand, I do 

 not consider it an impossible one. Fortunately, the chromo- 

 somes of different species have individual peculiarities in size, 

 shape and behavior that make it possible to identify many of 

 them without difficulty. Whether it will be possible to homoi- 

 ogise them throughout the family is not, of course, nearly so 

 certain. Such an extensive and thoroughgoing attack upon the 

 problem may, however, not be entirely necessary. It may be 

 sufficient to attempt an analysis of a more limited group than 

 the family. In that hope a great many genera have been 

 studied in order to find striking peculiarities that might assist 

 in the establishment of relationships between chromosomes and 

 somatic characters. The work has thus, for a time, been nar- 

 rowed down to a few forms ; and since my desire in this paper 

 is not to give detailed results, but rather to point out the direc- 

 tion in which, I believe, work of this character should proceed, 

 and to indicate the essential nature of my conclusions, I will 

 briefly describe the conditions of the investigation at the pres- 

 ent time. 



