286 



GERM-CELL CYCLE IN ANIMALS 



which transform entirely or in part into deuto- 

 plasmic granules of a fatty nature. 



The origin of the mitochondria in male cells can- 

 not be stated definitely, since certain investigators 

 (Goldschmidt, Buchner, Wassilieff, etc.) claim that 

 they arise from the nucleus ; others (e.^., Meves, Wilke, 

 Duesberg) consider them to be integral parts of the 



cytoplasm ; and a third 

 group (Montgomery, 

 Browne, Wildman) 

 looks upon some of 

 them as the results 

 of chemical interaction 

 between the nucleus 

 and the cytoplasm. 



Less is known con- 

 cerning the mitochon- 

 dria during oogenesis 

 than during sperma- 

 togenesis, but certain bodies have been described in 

 the ova of a number of animals which exhibit all of 

 the characteristics of the mitochondria of male cells. 

 As in the latter, they have been considered chromidial 

 by some and of cytoplasmic origin by others. 



The importance of the mitochondria depends 

 largely upon their functions. Those of the egg have 

 been observed by Russo (1907), Loyez (1909), 

 Faure-Fremiet (1910), Van Durme (1914), Hegner 

 (1914a), and others to transform directly into yolk 

 globules. According to Van der Stricht (1904), 

 Lams (1907), etc., they produce yolk elements in- 



FiG. 80. — Four stages in the formation 

 of the spermatozoon of Enteroxenos 

 showing the distribution of the mito- 

 chondria (M). (After Bonnevie.) 



