Genetics and Ethics 311 



tary nature is determined ; once the egg is fertilized the hereditary 

 possibilities of the new individual are fixed; once any stage of 

 development has passed, that page in the book of life is closed 

 and sealed. 



And yet at every step in this Jong process of development there 

 were one or more alternatives which might have been taken in- 

 stead of the one which was taken. There were innumerable 

 possible alternatives in the matings of our ancestors, there were 

 billions of possible alternatives in the union of the millions of 

 types of germ cells which each of our parents produced; at every 

 step in the development of the oosperm from which each of us 

 came there were many possible alternative stimuli and responses. 

 But in each case one of these innumerable alternatives was taken 

 and the others left. In every instance there was some cause that 

 determined which alternative was taken, but these causes are so 

 local and individual that they cannot be generalized; one cause 

 works in one instance, another in another, and so we say that 

 chance determines which alternative is taken, meaning by chance 

 only this that the causes involved cannot be generalized. At 

 critical stages in this process of development the alternatives are 

 so evenly balanced that minor considerations, which we call 

 chance, determine which path shall be taken; but there are no 

 backward steps in development and once a path has been taken 

 that particular crisis or turning point does not occur again. 



Thus each of us has wandered through the maze of life, chance 

 usually determining which path shall be taken of the many which 

 heredity and environment offer, until he has come to a stage 

 where associative memory makes it possible to profit by exper- 

 ience and where intellect and will make possible intelligent choice. 

 With the growth of intellect and will there comes to be a limited 

 degree of freedom and responsibility, and with increasing com- 

 plexity of organization the number of alternative paths is greatly 

 increased. The possible reactions of germ cells are relatively 

 few and fixed, the possible reactions of a complex animal are rela- 

 tively many and behavior is more plastic ; and thus this very com- 



