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THE AMERICAN NATURALIST [Vol. XL1V 



have anything to do with sexual reproduction or in eluci- 

 dating the more fundamental principles in the evolution 

 of organisms connected with sexual reproduction, still 

 remains to be seen. 



On the other hand, if one regards the elementary life 

 processes merely as the expression of metabolism, then 

 hereditary peculiarities are only the expression of metab- 

 olism. That which is inherited is for each organism 

 only that kind of metabolism peculiar to the organism. 

 Of course, the writer can not subscribe to this view. 

 Neither does he maintain that the cytoplasm takes no 

 important part in sexual reproduction. He has called 

 attention to the opinion that the stimulus to growth and 

 cell division which follows every sexual act fully accom- 

 plished, and which may be brought about apart from the 

 act of fecundation, has been confused with the main re- 

 sult of sexual reproduction, namely, the transmission of 

 parental characters. It is held that the present state 

 of our knowledge still maintains the doctrine that the 

 "monopoly" of transmitting hereditary characters still 

 belongs to the nucleus, and that these hereditary parental 

 characters are represented in the nucleus by material 

 entities. It matters little whether we speak of these 

 material representatives as pangens, or what not. The 

 opinion is expressed that the chief function of the cyto- 

 plasm, apart from purely nutritive activities, in its rela- 

 tion to the nucleus is directive or regulative in the sense 

 of being responsive to external stimuli. In so far as the 

 transmission of parental characters go, the cytoplasm 

 plays about the same role compared with the nucleus as 

 the environment does in the development of the individ- 

 ual organism. 



PAPEES CITED. 



