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 thenucleus; others (e.g., Meves, Wilke, 
Duesberg) consider them to be integral parts of the 
cytoplasm ; and athird 
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- 
Fic. 80.— Four stages in the formation < S 
of the spermatozoén of Enteroxrenos coe the mitochon- 
spongy setig of the wito~ dria. during ob genesis 
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), 
Fauré-Frémiet (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- 
