198 THE GERM-PLASM 



in a new embryogeny — provided that the necessary conditions 

 have been fulfilled — can only begin when this has occurred. 



3. Historical Account of the Theory of the Conti- 

 nuity OF THE Germ-plasm 



When my essay on the ' Continuity of the Germ-plasm ' 

 appeared seven years ago.* I was under the impression that I 

 was the first to give utterance to this conception. Since then, 

 however, I have found that similar ideas had arisen, in a more 

 or less distinct form, in other brains ; and I graduallv discovered 

 that a number of authors had independently recognised more or 

 less clearly the distinction between the body-cells and germ- 

 cells and the direct connection between the germ-cells of dif- 

 ferent generations : some had merely made the assertion, and 

 others had attempted to support it by facts. I shall here give 

 an account of those theories which preceded mine, taking them 

 in chronological order. 



As early as 1849, Sir Richard Owen had indicated that 

 differences may arise in the developing germ-cells between 

 those which become greatly changed and form the body, and 

 those which only undergo a slight change and form the repro- 

 ductive organs. t 



Francis Galton was the first to express certain ideas which 

 bore some resemblance to the conception of the continuity of 

 the germ-plasm. In a paper which appeared as early as 1872, 

 the individual is conceived ' as consisting of two parts, one of 

 which is latent, and only known to us by its effects on his pos- 

 terity, while the other is patent, and constitutes the person 

 manifest to our senses. The adjacent and, in a broad .sense, 

 separate lines of growth in which the patent and latent elements 

 are situated, diverge from a common group, and converge to a 

 common contribution, because they were both evolved out of 

 elements contained in a structureless ovum, and they jointly 

 contribute the elements which form the structureless ova of their 

 offspring.' \ 



* ' Der Continuitat des Keimplasma's," Jena, 1855 (Essay iv., p. 163, in 

 the second English edition). 



1 1 quote this statement from Geddes and Thomson's ' Evolution of 

 Se.x ' (London, 1889), p. 93, in which the original authority is not given. 



X Proc. Roy. Soc, No. 136, p. 394. 



