Modification of Germinal Constitution of Organisms 223 



of individual removal or behavior. Any such deduction, 

 however, is unwarranted and contrary to known facts, and, 

 furthermore, these modiiied characters themselves show that 

 after establishment they are alternative and capable in many 

 instances of replacement and recombination in full conform- 

 ity with established principles of heredity behavior. 



How shall this behavior, which has been observed by 

 MacDougal, Gager, myself, and others, in the production 

 of these variations, be interpreted? MacDougal's inter- 

 pretation, in the case of plants, is that the modifications 

 induced are due to the modifiability of the enzyme action 

 in one way or another. Gager attributes the activity to 

 the derangement of the chromosomes by the radium emana- 

 tions. In beetles, I do not know that the chromosomes 

 are deranged by any of the processes, and we do not know 

 that the chromosomes are the specific bearers of any par- 

 ticular attributes. The explanation which appeals most 

 strongly to me in the case of eggs which have been subjected 

 to strong incident forces is that the change should be 

 regarded as an example of stereoisomeric change, whether in 

 the composition of the katalyzing agent, or in the composi- 

 tion of the chromogen, or in some accelerator or inhibiting 

 agent in the germ plasm. It is quite conceivable that the 

 change may take place in the chromogen. As far as known, 

 all chromogens are substances of wide distribution in all 

 organisms with slightly different chemical characteristics, 

 and it is highly probably that there is a wide range of 

 chemical composition in these chromogens, so that a slight 

 change in the arrangement of the molecular composition 

 of the chromogen could be productive of the results observed. 

 At present, however, there is little possibility of obtaining 

 definite evidence along this line, because the present methods 



