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THE AMEBIC AN NATURALIST [Vol. LI 



fore into the egg cell also. Should the sperm cell strip 

 itself free of most of that part of the cytoplasm that con- 

 tained these inclusions, the spermatozoa alone of all the 

 cells in the body would be free from these cytoplasmic 

 materials, and in consequence would not transmit them. 



So long as we recognize with what we are dealing here 

 it is largely a matter of personal choice whether we prefer 

 to include plastid transmission through the egg (or even 

 through the cytoplasm of the sperm in special cases) 

 under the term heredity. 



The number of cases in which plastid inheritance is 

 known to occur is very limited,^ while Mendelian heredity 

 includes the vast majority of characters about whose in- 

 heritance we know something definite. 



But it is a far cry from these cases of transmission of 

 /plastids to the view that the cytoplasm transmits equally 

 I with the chromosomes; or that the cytoplasm transmits 



Ithe fundamental attributes of the organism and that the 

 chromosomes transmit only the more superficial charac- 

 *teristics-a view that Boyeri discussed in detail in 1903, 

 (and which was a favorite topic of his on several later 

 occasions. He changed entirely as tho evidence came in 

 and finally abandonedjliejview in liis la>t i.apor (1914). 



This is an old and familiar topic with euibryologists, 

 but since it has been recently revived, a brief statement 

 in regard to it may not be out of place. Fortunately this 

 view is no longer a matter of opinion but of experimentally 

 determined evidence. 



In 1912, Toyama described some cases in silkworm 

 moths of what is known as maternal inheritance— cases 

 in which certain characteristics that develop in the hybrid 

 embryo are like those of the maternal stock. He found 

 cases involving the color of the yolk, shape of the egg, and 

 the pigment (not present as such in the egg) that de- 

 velops after the serosa is formed. By breeding tests it 



