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EVOLUTION AS A NATURAL PROCESS 143 



body produces minute particles called gemmules, which 

 partake of the characters of the cells that produce 

 them. The gemmules were supposed to be transported 

 throughout the entire body, and to congregate in the 

 germ-cells, which in a sense would be minute editions 

 of the body which bears them, and would then be 

 capable of producing the same kind of a body. If 

 true, this view would lead to the acceptance of 

 Lamarck's or even Buffon's doctrine, for changes in- 

 duced in any organ by other than congenital factors 

 could be impressed upon the germ-cell, and would 

 then be transported together with the original specific 

 characters to future generations. Darwin was indeed 

 a good Lamarckian. . .. 



But the researches of post-Darwinians, and especially 

 those of the students of cellular phenomena, have dem- 

 onstrated that such a view has no real basis in fact. 

 Many naturalists, like Naegeli and Wiesner, were 

 convinced that there was a specific substance concerned 

 with hereditary qualities as in a larger way protoplasm 

 is the physical basis of life. It remained for Weismann 

 to identify this theoretical substance with a specific 

 part of the cell, namely, the deeply staining substance, 

 or chromatin, contained in the nucleus of every cell. 

 Bringing together the accumulating observations of 

 the numerous cytologists of his time, and utilizing them 

 for the development of his somewhat speculative theo- 

 ries, Weismann published in 1882 a volume called '^The 

 Germ Plasm," which is an immortal foundation for 

 all later work on inheritance. The essential principles 

 of the germ-plasm theory are somewhat as follows. 

 The chromatin of the nucleus contains the determinants 



