PURE LINES IN THE STUDY OF GENETICS IN 

 LOWER ORGANISMS 1 



PROFESSOR H. S. JENNINGS 

 The Johns Hopkins University 



At the meeting of this society a year ago I asked in a 

 paper read, 2 whether the pure line idea did not deserve 

 agitating a little before this society, and I tried to agitate 

 it. This was because I saw that for practical purposes 

 of future work it would be necessary to make up my mind 

 as to the importance of this idea, and it seemed that other 

 members of the society might be in the same situation and 

 that we might help one another. My method of agitation 

 was to give the apparent relations of the results of work 

 along this line up to that time, to one of the burning 

 problems in our field — the problem of selection. In the 

 few minutes that each of us have here the purpose of 

 agitation can be served and general results brought 

 sharply into view only by naked and dogmatic statements, 

 such as one would never use under other conditions. 

 Such naked and dogmatic presentation has serious dis- 

 advantages — felt most decidedly by the author when his 

 critics hold the mirror up to nature. I have therefore at 

 times regretted giving forth this paper. But if it has in 

 any way acted as an irritant to arouse the discussion fore- 

 shadowed in our present program, I shall feel that its 

 good results outweigh its painful ones, and that it was 

 worth while after all. We are apparently to have 

 brought before us a part of that ' ' thorough try out" that 

 I asked for, and from a study of our program I think I 

 can see that it is not all to be a paean of praise for the pure 

 line work. Such illumination and such interest as comes 



