WEISMANWS ESSAYS UPON HEREDITY. 19 



the vehicle. Professor Weismann, indeed, admits 

 this, but with obvious reluctance. He says 



" I am far from asserting that the germ-plasm which, as 

 I hold, is transmitted as the basis of heredity from one 

 generation to another is absolutely unchangeable or totally 

 uninfluenced by forces residing in the organism within which 

 it is transformed into germ cells. I am also compelled to 

 admit that it is conceivable that organisms may exert a 

 modifying influence upon their germ cells, and even that 

 such a process is to a certain extent inevitable. The nutri- 

 tion and growth of the individual must exercise some 

 influence on the germ cells ; but in the first place this 

 influence must be extremely slight, and in the second place 

 it cannot act in the manner in which it is usually assumed 

 that it takes place." 



But if, as he admits elsewhere, a changed climate 

 may somehow affect the germ, and if increased 

 nourishment not only increases the luxuriance of a 

 plant, but "in some distinct way alters the plant," 

 it may also be true, as is commonly believed, that 

 the acquired habit of intemperance may react upon 

 the germ-plasm of which the drunkard is only the 

 steward, and he may transmit an alcoholized 

 nature to his children ; and the rout may not only 

 be destroying his individual life, but weakening 

 and vitiating that which he hands down to pos- 

 terity. It may be a slower process than we had 

 imagined, but it is hard to believe that it does not 

 take place. 



Looking at Professor Weismann's theory as a 



