218 THE LAW OF JOHANNSEN. 



effect of a difference in the environmental factors will appear 

 altogether negligible to us, and if we study the inheritance of 

 characters, we study genotype differences, and we are more 

 or less liable to call these differences, "unit-characters". In this 

 material, recurrent, characteristic differences, unit-characters, 

 are the obvious and direct result of presence or absence of 

 genes. And if we disUke this term "unitcharacter" with its sug- 

 gestion of Weismann's "determinanats," the dislike is bom 

 of our biomechanic conception of characters, and not of any 

 unfitness of the term "unit-characters" for describing these 

 differences. 



If we say "heredity of characters," we think of genotypic 

 likenesses between the individuals having the same heredity, 

 although the term implies nothing of the sort. The red colour 

 of Sudan III, transmitted to eggs and larvae from moths 

 having eaten it, in Gage's experiments, is just as much an 

 inheritance of a character as the inheritance of red colour in 

 wheat, where we know one of the genes, is an inheritance of 

 a character. 



Or is it not? And if we shrink from calling both processes by 

 the term inheritance of characters, which is a matter of person- 

 al taste, should we call the likeness between a mother and her 

 daughters in uni-cellular organisms inheritance of characters? 

 To my way of thinking, most of the confusion, most of the 

 startlingness of certain selection-experiments, most of the 

 heated controversy round about Johannsen's work, is caused by 

 loose thinking and unwarrantable generalisation of facts found 

 in wheat to yeast, and of conditions found in bacteria to what 

 they are, or are not, in peas. 



We must remember, that the Ukeness between two cells, of 

 which one is half of the other, or has been, only half an hour 

 ago, as compared to the unlikeness between these cells and a 

 descendant cell fifty generations hence, is much more influen- 

 ced by a greater likeness or unlikeness of the environment, 

 than the likeness between two adult hens, mother and daugh- 

 ter. 



