INTRODUCTION xvii 



period of development at which they were originally 

 formed, and reinforce the action of the environ- 

 ment. In this way MacBride attempts to explain 

 recapitulation in development and the tendency to 

 precocity in the development of ancestral structures. 

 His idea that the hormones act by ' incorporation ' 

 in the genital cells is different from that of stimulation 

 of determinants put forward by myself and others, 

 but it is surprising that he should refer to un- 

 published suggestions of Professor Langley, and not 

 to the publications of authors who had previously 

 discussed the possible action of hormones in con- 

 nexion with the heredity of somatic modifications. 



Dr. J. G. Adami in 1918 published the Croonian 

 Lectures, delivered by him in 1917 under the title 

 * Adaptation and Disease,' together with reprints of 

 previous papers, in a volume entitled Medical Con- 

 tributions to the Study of Evolution. In this work 

 (footnote, p. 71) the author claims that he preceded 

 Professor Yves Delage by some two years in offering 

 a physico-chemical hypothesis in place of deter- 

 minants, and also asserts that ' the conclusions 

 reached by him in 1901 regarding metabolites and, 

 as we subsequently became accustomed to term 

 them, hormones, and their influence on the germ- 

 cells, have since been enunciated by Heape, Bourne, 

 Cunningham, MacBride, and Dendy, although in 

 each case without note of his ( Adami' s) earlier 

 contribution.' These somewhat extensive claims 

 deserve careful and impartial examination. The 

 paper to which Dr. Adami refers was an Annual 

 Address to the Brooklyn Medical Club, published 

 in the New York Medical Journal and the British 

 Medical Journal in 1901, and entitled ' On Theories 

 of Inheritance, with special reference to Inheritance 



b 



