124 ORIGIN OF SOMATIC 



The difficulty of this theory is one which has 

 occurred to biologists who have previously made 

 suggestions of a connexion between hormones and 

 heredity — namely, how hormones or waste products 

 from one part of the body could differ from these 

 from the same tissue in another part of the body. 

 If there were no special relation, hypertrophy of 

 bone on one part of the body such as the head would 

 merely stimulate the factor for the whole skeleton in 

 the gametocytes, and the result would merely be an 

 increased development of the whole skeleton. On 

 the other hand, we have the evident fact that a 

 number of chromosomes formed apparently of the 

 same substance, by a series of equal chromosome 

 divisions determine all the various special parts of 

 the complicated body. This is not more difficult to 

 understand than that every part of the body should 

 give off special substances which would have a 

 special effect on the corresponding parts of the 

 chromosomes. We know that skin glands in dif- 

 ferent parts of the body produce special odours, 

 although all formed of the same tissue and all 

 derived from the epidermis. It seems not impossible 

 that bones of different parts of the body give off 

 different hormones. If the factors in the gametes 

 were thus stimulated they would, when they de- 

 veloped in a new individual, produce a slightly 

 increased development of the part which was 

 hypertrophied in the parent soma. No matter 

 how slight the degree of hereditary effect, if the 

 stimulation was repeated in every generation, as in 

 the case of such characters as we are considering 

 it undoubtedly was, the hereditary effect would 

 constantly increase until it was far greater than the 



