THEORY OF BROOKS. 2?$ 



parts of the body have a tendency to accumulate in 

 the male generative organ. The spermatozoon may 

 be regarded as a store of these gemmules. Now, 

 when these spermatozoa unite with the ovum in fer- 

 tilization, there is introduced into the ovum a store 

 of gemmules from the body of the male. The intro- 

 duction of such a lot of new organisms into the 

 ovum must change its constitution, and this, of 

 course, would cause it to develop in a different 

 manner from what it otherwise would have done. 

 In this way is induced a tendency to variation in the 

 offspring of sexual reproduction. The ovum itself 

 would develop in the same manner as did the pre- 

 vious generation, but the fact that it has united with 

 the male element of another individual has intro- 

 duced into it a lot of new elements. These intro- 

 duced gemmules so alter the ovum that it develops 

 somewhat differently from the previous generation. 

 The theory goes on to say that these gemmules do 

 not affect the whole ovum, but each its own special 

 part. Suppose, for instance, that certain gemmules 

 from the parts of the eye of the male enter the 

 ovum in fertilization. These gemmules will be at- 

 tracted by some internal affinity to that part of the 

 ovum which is to give rise to the eye of the next 

 generation, and hence the eye will become variable. 

 So with other parts, an internal affinity is supposed 

 to cause the gemmules from the different parts of the 

 body to unite with corresponding parts of the ovum. 

 In this way a child might inherit acquired variations 

 from its father, though not, as a rule, from its 

 mother. 



