OUR FUTURE COURSE 211 



chromosomes must grow and reproduce like all 

 living things, we cannot avoid the possibility that, 

 in spite of their remoteness, a residuum of influ- 

 ence may reach them from the surrounding body. 

 Successive generations of them are, in their turn, 

 products of their predecessors' reaction to their 

 environment. 



The nature of this influence may be obscure, but 

 it presents one logical possibility. We know that 

 organic activity or inactivity results in a corre- 

 sponding increase or decrease of functional capacity 

 and, without doubt, in a corresponding physico- 

 chemical development. If we extend this principle 

 to the chromosomes or to the genes, as may logi- 

 cally be done, the exercise of a given function 

 establishes a condition in the body which favors a 

 coordinated development of the genes involved. 

 There is no known reason why this condition should 

 be limited to the cells involved in the expression of 

 the character, for the individual maintains its en- 

 tire chromosome complex normally in all cells of 

 the body, without regard to their specialization 

 and their individual cytoplasmic functions. A 

 chromosome exists in a given state partly because 

 a given condition in the body makes possible the 

 development and perpetuation of chromosomes in 

 that particular state. Since the same kind of 

 chromosome appears in many cells, irrespective 

 of their relation to the character whose somatic 



