320 BEHAVIOR OF THE LOWER ORGANISMS 



There seems to be no question but that the power of new individuals 

 to react in certain ways without preliminary trial has been much over- 

 estimated. In most organisms there is in the early stages of develop- 

 ment a continued process of trial, through which the habits become 

 established. On the other hand, there is no doubt that individuals do 

 appear with certain ways of reacting which most of their early ancestors 

 did not at the beginning have. The question as to how this happens, 

 therefore, presses for an answer. 



The answer formerly given was, that the acquirements of the parent 

 are directly inherited by the offspring. The parent having come to 

 react in a certain way, the condition of the system inducing this reaction 

 is passed on to posterity. In the unicellular organisms there seems to 

 be nothing in the way of this inheritance by the offspring of the reaction 

 methods acquired by the parent. There is no distinction between germ 

 cells and body cells in these organisms ; all acquirements pertain to the 

 reproductive cells. Through reproduction by division the offspring 

 are the parents, merely divided, and there is no evident reason why they 

 should not retain the characteristics of the parents, however these char- 

 acteristics were attained. If this is the real state of the case, then in 

 unicellular organisms the life of the race is a direct continuation of the 

 life of the individuals, and any acquirements made by the individuals 

 are preserved to the race. 



But in multicellular organisms the facts show that in the immense 

 majority of cases the inheritance of the acquirements of the parents by 

 the offspring does not occur. We know that we do not start with the 

 education acquired by our parents, but must begin at the bottom, and 

 acquire both knowledge and wisdom of action. In other words, we 

 know that we fail to inherit directly the more efficient methods of reac- 

 tion acquired through experience by our parents, in at least nine hundred 

 and ninety-nine cases out of a thousand. Moreover, the theoretical 

 difficulties in the way of such inheritance are great, and no demonstrative 

 evidence seems to exist that it ever occurs. Thus we are certain that in 

 most cases it does not take place, and must doubt whether it is possible. 



If we give up, as most students of heredity do, the inheritance of ac- 

 quired characters, the alternative explanation for progress in the race is 

 by natural selection of congenital variations. The theory of natural 

 selection may be stated briefly as follows: Organisms vary in many 

 ways, through variations affecting the germ cells. Among these varia- 

 tions are some that help the organism, making it more efficient in escap- 

 ing enemies or in obtaining food. These organisms, therefore, survive, 

 while those without these helpful variations are killed. The surviving 

 organisms transmit their helpful congenital variations to their offspring. 



