THE BRADSHAW LECTURE 37 



is said to have been reproduced as many as ten 

 times after amputation, and he was obliged to 

 admit that certain influences, such as lack of 

 nourishment, might influence and modify the 

 germ-plasm which he regarded as continuous. 

 His theory led to a discovery of inestimable value 

 the finding of the chromosomes of the nucleus, 

 their reduction to half their normal number, and 

 the restoration to the normal number on fertilisa- 

 tion, half being supplied by the germ- and half by 

 the sperm-cell. But his theory has probably 

 swung the pendulum of thought too much in one 

 direction, and though it may be true that body 

 influences of a few generations are not evident in 

 the offspring, when we are dealing with hundreds, 

 thousands, or millions of generations the effects 

 of use and disuse seem to me scarcely to be 

 denied. Perhaps no better illustration can be 

 given than the gradual changes that are taking 

 place in the human foot. It is twenty-three years 

 ago that in a lecture on anatomy I pointed out 

 that the gradual disappearance of the little toe 

 was getting ahead of the text-books, for whilst it 

 had already lost one of its extensor tendons, in 

 quite an appreciable percentage of cases one of 

 its flexor tendons was absent also. These at best, 

 like its bones, are diminutive and useless, and its 



