THE VIA MEDIA 69 



their development show excess or deficiency in the function of 

 the glands implicated in the parents, and " so conditions acquired 

 by the parents reproduce themselves in and become inherited 

 by the offspring." I am glad to see that one zoologist, my old 

 friend Professor E. W. MacBride, has joined himself with me in 

 this opinion, and with me sees in this possibility or probability 

 the solution of a long-standing difficulty. 1 



" Lamarck's contention was that the identical changes caused 

 in the structure of an individual animal or plant, by the action 

 of a novel environment, . . . are transmitted by generation to 

 that offspring, and continue to appear in successive generations 

 derived from that offspring even when the cause which set up 

 the original modification of structure ceased to act. . . . Darwin 

 . . . did categorically state that he attributed the origin of 

 congenital variation (by the natural selection or survival of 

 which he held that new species originate) to the action or in- 

 fluence of changed conditions upon the parental body, and 

 through it upon the reproductive germs." 2 



It will be seen that the results of medical research here 

 quoted support strongly Darwin's contention, though at the 

 same time they indicate a group of cases in which the direct 

 adaptation of a particular endocrine organ may, through the 

 action of its internal secretion, bring about an identical change 

 in the same organ of the offspring. There is, that is to say, 

 one possible group of cases for which the Lamarckian theory 

 holds true, and that, oddly enough, as MacBride points out, along 

 the lines of Darwin's discarded hypothesis of pangenesis. Only 

 it is not by specific corpuscular determinants or pangens but by 

 secretions and the chemical activity of the same that the organs 

 of the body, or certain of them, are capable of influencing the 

 germ cells and bringing about a chemical and relatively permanent 

 change in their constitution. 



After long years of heavy fighting we have, as it were, con- 

 quered our Vimy or Messines Ridge ; and, although for a time 

 we are held up, we can, as it were, indulge in a " Pisgah view," 

 and see where and how the next advance is to be made. 



1 Embryology of the Invertebrates, vol. i., 1914, and Presidential Address, 

 Zoological Section, British Association, 1912. 



2 Sir E. Ray Lankester, The Kingdom of Man, Rationalist Press Associa- 

 tion, cheap reprints, No. 50, 1912, p. 74. 



