33 EVOLUTION OF LIVING ORGANISMS. 



plex association transmitted from the parents of sub- 

 stances with properties or capacities which make up the 

 specific inheritance characteristic of each organism, and 

 which may be called its assemblage of germinal factors, 

 or its germinal constitution. Not only are organisms as 

 we see them before us necessarily the results of the 

 combined action of these two sets of factors ; but so also 

 is every part of them, every structure, every activity, 

 every organ, every habit. Therefore the characters 

 observed and measured, dealt with in statistics and ex- 

 periments, are likewise their products. The inheritance 

 might be compared to a musical instrument, the stimuli 

 to the player, and the organism and its characters to the 

 music produced. What particular tune is produced will 

 depend on the player ; but the range of possible sound 

 will be limited by the structure of the instrument, by the 

 factors which make up its capacity to respond to the 

 touch of the player. 



In a sense, then, every character, every variation, is 

 partly acquired and partly inherited ; and no character 

 is more acquired or more inherited than another. Hence 

 the popular distinction between acquired and not ac- 

 quired characters, between those which have been de- 

 veloped in the course of the individual's lifetime and 

 those which are inborn, is misleading. The very terms 

 involve a fallacy. We cannot point to this or that bodily 

 or mental structure and say this is acquired and that is 

 not. What we see before us is the result of both sets of 

 factors in every case. 



And yet there are characters which reappear in off- 

 spring and others which do not. The fact is that we 

 must revise the popular conception of inheritance just as 

 we have revised that of "acquired characters." 



Obviously if either of the sets of factors be altered the 

 resulting organism will be changed ; variation will occur. 

 What is called the normal mental or bodily structure is 

 that developed under the usual complex of environmental 



