132 MARINE BIOLOGICAL LABORATORY. 



Second, it must account for the non-repetitive phenom- 

 ena, or the appearance of new characters, to the impor- 

 tance of which Darwin first directed our attention. It 

 is clear that anthropology, zoology, botany, and palaeon- 

 tology give an ample field for the above. Thirdly, there 

 are the physical transmission phenomena, the peculiar 

 field of the embryologist. We may approach heredity 

 through either of these channels, but the test must be 

 by the data afforded by them all. 



Thus we find Lamarck, Darwin, Galton, Spencer, 

 Brooks and others coming to the problem chiefly from 

 the study of living adults in past and present time, while 

 Weismann has come to it from the side of embryogen- 

 esis. There are great difficulties in the embryological 

 problem ; we have to do with particles of protoplasm of 

 minute size, largely composed of water, yet suspending 

 invisible molecules which we must suppose are the 

 actual vehicles of inheritance, for, under the ordinary 

 conditions of nutrition, they will repeat chapter after 

 chapter in the history of the race, and finally take the 

 form of the adult — they are indeed microcosms. We 

 have to consider the part played by the male and female 

 element. And the relation of these specks of protoplasm 

 to the life history of the individual. 



Democritus, who offered the first hypothesis, supposed 

 that the sperm was secreted from all parts of the body 

 of both sexes at the time of impregnation animated by 

 a bodily force, like parts producing like. When Dar- 

 win proposed his provisional hypothesis of pangenesis 

 he embodied in it a somewhat analogous conception, but 

 he was aided by the v/ell advanced stage of embryo- 

 logical and physiological science. The older views of 



