14 ESSA YS SCIENTIFIC AND PHILOSOPHICAL. 



good or evil has affected the others from outside. 

 This illustration of a creeping rhizome, however, 

 is a very imperfect one. It would fairly represent 

 the facts if the plant or animal were the offspring 

 of one parent only. But when sexual reproduction 

 appears, the germ-plasm, out of which the individual 

 plant or animal is built up, is the union of the 

 germ-plasms of four grand-parents, and so on. 

 The complexity of the germ-plasm increases in 

 geometrical ratio, so that in the tenth generation 

 a single germ contains 1024 different germ-plasms, 

 with their inherent hereditary tendencies. But 

 though the germ-plasm in each generation increases 

 in complexity, it does not increase in mass. For it 

 is constantly being used, as it increases, for the 

 building up of successive individuals, though there 

 is always a part of the germ-plasm which is not 

 used up in the construction of the body of the 

 offspring, but is reserved unchanged for the next 

 generation. The somatic cells belong to the 

 individual, are modified in the life of the individual 

 both by the direct action of environment and 

 by use and disuse, but they also die with the 

 individual ; while the germ cells belong to the 

 race, and can only be affected very slightly, if at 

 all, through the somatic cells. As a corollary 

 from this we get 



The non-transmission of acquired characters. 

 This, of course, does not mean that a new charac- 



