460 



ELEMENTARY BIOLOGY 



to these cells some of the germ plasm from which it had itseli 

 developed. In other words, the eggs produce the organism, 

 not the organism the eggs (see Fig. 246). 



According to this notion it would be impossible for the ex- 

 perience of an individual to influence the germ cells in such a 

 way as to make the offspring show the effects. For example, 

 the result of exercise or of mutilations or of sickness should 

 not appear in the following generation. As a matter of fact 

 we have no evidence whatever that modifications produced in 



61 62 63 



Fig. 246. The idea of the germ plasm 



When a fertilized egg, g, develops into a new individual, d, part of the protoplasm 

 becomes the body, or soma, and part remains germ, within the body, where it is nurtured 

 The germ is not a product of the body in any sense. Each body, b^, bo, /'g, is a branch, 

 or development, of the germ, but the stream of germ material is continuous. The 

 nature of the germ determines the kind of individuals or persons that will develop ; the 



body does not influence the germ 



an individual in the course of his lifetime are ever reproduced 

 in the offspring, although you will find many people who firmly 

 believe that such modifications are actually transmitted. 



482. Sports. The appearance from time to time of an un- 

 usual kind of individual that the breeders and horticulturists 

 call a sport would suggest that germ plasm may undergo 

 important changes. There appeared on a farm in Massachu- 

 setts, in 1 79 1, a queer sheep with a long body and very short, 

 crooked legs. This " ancon " ram was kept for many years, 

 and had many offspring with normal sheep. All the hybrids 

 showed the same curious character. This "turnspit" type of 



