xvi HORMONES AND HEREDITY 



elaborated a definite Lamarckian theory of the origin 

 of Secondary Sexual Characters in relation to 

 Hormones, extending the theory also to ordinary 

 adaptive structures and characters which are not 

 related to sex. Having met with many obstacles in 

 endeavouring to get a paper founded on the original 

 lectures published in England, I finally sent it to 

 Professor Wilhelm Roux, the editor of the Archiv filr 

 Entwicklungsmechanik der Organismen, in which it 

 was published in 1908. 



In his volume on the Embryology of the Inverte- 

 brata, 1914 (Text-Book of Embryology, edited by 

 Walter Heape, vol. i.), Professor E. W. MacBride in 

 his general summary (chapter xviii.) puts forward 

 suggestions concerning hormones without any 

 reference to those who have discussed the subject 

 previously. He considers the matter from the point 

 of view of development, and after indicating the 

 probability that hormones are given off by all the 

 tissues of the body, gives instances of organs being 

 formed in regeneration (eye of shrimp) or larvae 

 (common sea-urchin) as the result of the presence 

 of neighbouring organs, an influence which he thinks 

 can only be due to a hormone given off by the organ 

 already present. He then states that Professor 

 Langley had pointed out to him in correspondence 

 that if an animal changes its structure in response to 

 a changed environment, the hormones produced by 

 the altered organs will be changed. The altered 

 hormones will circulate in the blood and bathe the 

 growing and maturing genital cells. Sooner or later, 

 he assumes, some of these hormones may become 

 incorporated in the nuclear matter of the genital 

 cells, and when these cells develop into embryos 

 the hormones will be set free at the corresponding 



