286 SHULL GERMINAL ANALYSIS [April 23, 



couched their suggestions in such terms as to show that they were 

 open to any new light upon the subject. 



Although I have never looked upon the Weismannian conception 

 of character-determiners as at all plausible, I do not agree with Dr. 

 Spillman 3 that the facts presented by Riddle " disprove " the " par- 

 ticle hypothesis." The only manner. in which Riddle despatched ( ?) 

 the "particle hypothesis" was by ruling the observed facts of Men- 

 delian heredity out of court. If the Mendelian phenomena are real, 

 and no one can do careful investigation in this field without becom- 

 ing convinced that they are, the postulation of "particles" or "bul- 

 lets" having certain chemical and physiological properties, and be- 

 having during the reproductive process in some such manner as the 

 cytologists are fairly agreed that the chromosomes behave, would 

 offer a complete explanation, and the correctness of such an ex- 

 planation can not be disproved except by proving that some other 

 method of determination is the true one. However, while the 

 particle hypothesis is not disproved, I have no doubt that the Weis- 

 mannian, and perhaps also the De Vriesian conception of the genes 

 will seem less and less plausible as new facts accumulate. 



In Dr. Spillrhan's 4 brilliant development of what he calls the 

 "teleone hypothesis," a suggestion is offered which virtually makes 

 the chromosomes the " bullets " whose differential properties deter- 

 mine the unit-characters. This interpretation of the Mendelian phe- 

 nomena has much to commend it, especially as it calls for no struc- 

 ture and no type of behavior which are not already generally recog- 

 nized as being universally present in the formation of the germ- 

 cells, and it has the added advantage that it seems to be capable of 

 experimental tests. 



I can not see, however, that Dr. Spillman has presented "an 

 explanation of Mendelian phenomena without resorting to the idea 

 of unit-characters." If he appears to do so, it is only because he 

 gives to them a new name. The unit-characters are the empirical 

 phenomena for whose explanation the "bullets," "teleones" or 

 genes of any other sort, are devised. It is no new idea that these 



8 In conversation. 



* Spillman, W. J., " Mendelian Phenomena Without De Vriesian Theory," 

 Amer. Nat., 44: 214-228, April, 1910. 



