No. 518] SHORTER ARTICLES AND DISCUSSION 119 



in the organism is unquestionably a matter of inheritance, nor 

 can there be any question that there is a Mendelian segregation 

 with reference to this tendency. This does not mean, however, 

 that there is a bullet somewhere in the germ plasm which is 

 wholly responsible for the development of horns. I imagine 

 that the development of horn tissue is a process in which prob- 

 ably all of the organs of the cell participate; but if there is 

 one organ which has become so changed in its functions that 

 it can no longer take its usual and necessary part in the de- 

 velopment of these organs, and if this organ is a chromosome, 

 then we necessarily get the phenomenon of Mendelian segregation 

 in inheritance with reference to this character. 



Riddle points out a good many facts that it is well for Men- 

 delianists to keep in mind in formulating hypotheses to account 

 for the facts they discover, 

 these is the finding by Spiegle 

 the wool of white sheep contain a 

 gations indicate that these whi 

 advanced stage of oxidation the 

 of this character we should thm 

 the Mendelian sense. Riddle s 



these cases 

 Mendelian 

 That mel 

 long series 

 periments < 

 ment he \ 



