310 Relation of Use and Disuse to Evolution 



perfection. Herbert Spencer, accepting Lamarck's essential 

 principles, would have nothing to do with the tendency 

 toward perfection, which was for him, as for many thinkers 

 who accept it, a mystical entity. It is explained by Lamarck, 

 however, in a common-sense way — granting, that is, the 

 transmission of acquirements. 



There is the possibility that under the influence of the 

 encyclopedists and of the current enthusiasm for universal 

 uplift, Lamarck adopted the principle of progressive im- 

 provement from the model of social or cultural advance- 

 ment. It is sufficient for the present, at any rate, to note 

 that the improvements which he used as illustrations can be 

 readily enough explained without assuming the transmission 

 of modification. If the children of '* educated " parents 

 learn more easily than the children of illiterates it may be 

 because the stimulation for learning comes to them earlier 

 in life, or because they come of a stock that takes kindly 

 to intellectual pursuits. The colt of the well trained mare 

 runs faster than others not because the mother was trained, 

 but because he is descended from ancestors who have it in 

 them: the training brought the capacity to the surface. The 

 son of the blacksmith is more muscular than the son of the 

 vicar because he belongs to a family given to muscular de- 

 velopment, and so on. 



The Germ Plasm 



The first systematic attack upon Lamarckism came 

 from the studies of the German biologist, August Weismann, 

 who in 1893 formulated his theory of heredity in his book 

 The Germ Plasm. In this Weismann developed a sharp dis- 

 tinction between the protoplasm which makes up the body 

 of a plant or animal, and that which passes from generation 

 to generation in the eggs and sperms. The latter he called 

 the germ plasm. In one-celled animals, like ameba or Para- 

 mecium, each individual gives rise to two by the process of 

 cell division. The protoplasm, assimilating food and increas- 



