204 A STUDY IN HEREDITY 



transmitted, would appear as a variation in the third generation. 

 Obviously, male parents can transmit modifications only as 

 variations. 



The cause of variations is in dispute. Many elaborate theories 

 have been enunciated, which, at the least, afford splendid testi- 

 mony to the imaginations of their authors. We need not dwell 

 on them ; suffice it to say that variations do occur, no matter how 

 produced. Men do diifer in inborn characters from their parents. 

 Now the body, as I say, is a cell-community, composed of germs 

 and other cells. Suppose, then, a man acquires a character; 

 suppose, for instance, he strengthens his arms by exercise, or 

 weakens his legs by laziness, in that case, if his acquired character 

 is to be transmitted, the change in his arms or legs must so affect 

 his germs, that it will be reproduced (as an inborn character) in the 

 children into which the germs proliferate. This consideration at 

 once reveals the difficulty of the belief in the transmission of ac- 

 quired characters. How can each one of the million changes which 

 may occur in the arms, legs, and other parts of the body affect 

 the germs (situated, it may be, far distant) in such a special 

 manner that, after fertilisation and long separation from the 

 parent organism, the germs will proliferate into beings that have 

 inborn the particular character the parent acquired ? How, for 

 example, can a modification of the parent's great toe affect his 

 germ differently from a modification in his little finger ? What 

 is the machinery by which this magical process is carried out ? 

 It must be remembered that a child is not derived from the 

 whole of his parent's body. He develops out of a very minute 

 portion of it only — the germ-cell. His eyes are not the offspring 

 of his parent's eyes ; his legs have not origin in his parent's legs ; 

 his brain is not descended from his parent's brain ; but every 

 portion is derived solely from the germ-cell, which, so far as we 

 know, is indebted to the body-cells for shelter and nutrition only. 

 Again, it must be remembered, that in the germ there are no 

 tissues similar to those in the parent — no muscle, bone, or nerve- 

 cells, for instance. It is in vain to argue that the potentiality of 

 them is present ; the fact remains that they are not present. 



