THE LAW OF JOHANNSEN. 2! 7 



This likeness we consider a better evidence of sameness of 

 genotype, than the likeness between two summer-generations 

 of a certain Daphnia as compared to the unlikeness between 

 these two on one hand and winter-generations of a Daphnia 

 on the other. And in my opinion, the comparative likeness 

 between a mother-cell and a daughter-cell is certainly not of the 

 same order as that between a mother bear and her daughter. 



If we simply speak of inheritance of characters, we mean 

 quite a different thing according to the type of organism under 

 discussion, and we must not forget this, or confusion will be 

 the result. One man may happen to work with wheats and 

 "inheritance of characters" may mean something definite to 

 him. It is possible to show him a definition, which he will think 

 acceptable, and then show him an instance, which complies 

 with the definition but not with his conception of "inheritance 

 of characters". Simply because, in accepting the definition, 

 he has his own material in mind, and he has not quite thought 

 out what "inheritance of characters" might mean in other 

 material. 



The "characters" of any individual are its qualities, nothing 

 more nor less, and those qualities are simply the result of the 

 development, the way in which the individual grew to be from 

 what it was before. Now in the bigger, longer-lived, multi-cellu- 

 lar organisms, the "environment" is relatively so constant, and 

 variations in it so tend to counteract each others effect, that 

 in the long-run environment will be on the average about the 

 same for every individual. And in the measure in which this 

 is the case, environmental factors in the development become 

 more and more modification-factors, and less and less determ- 

 ination-factors, to use the terminology of Roux. Now, the 

 smaller the organism, and the smaller the number of cells com- 

 posing it, the more will environmental factors in the develop- 

 ment become determination-factors. 



If we are used to work with wheats, where we compare a 

 mother-plant which has grown from September till July with a 

 daughter-plant that has grown from September to July, the 



