532 VARIATIONS 



other words, the responses of the somatoplasm to the environment, 

 are not transmitted. The skill parents acquire in music, mathe- 

 matics, etc., is not transmitted to the childern, but they may 

 transmit factors for industrious habits, determination to succeed, 

 and a liking for a particular line of work, the characters to which 

 they owe their success. Drinking parents do not transmit the 

 drink habit but due to their indulgence their germ-plasm may 

 be so modified as to produce nervous and weak-willed oflFspring 

 which may readily take to drinking. 



According to Weismann, all hereditary variations, such as 

 mutations, have their origin in the germ-plasm, while most 

 fluctuating variations are only modifications of the somatoplasm 

 and disappear with the somatoplasm in which they occur. 

 Obviously, according to Weismann, acquired characters are not 

 inheritable. 



That there are two distinct kinds of protoplasm is not so evident 

 in plants as in animals, and it was chiefly from a study of ani- 

 mals that Weismann drew his conclusions. From a portion of a 

 potato tuber plants with all potato characters develop. This 

 means that the tuber, a somatoplasmic structure, has about all 

 the factors that the germ-plasm of potatoes has. Among plants 

 there are many cases where plants with all characters represented 

 develop from buds or roots, leaves, or stems. Also, that no 

 acquired characters are inheritable is doubted by some scientists, 

 although observations and experiments are almost entirely in 

 accord with this view. 



