CHAPTER IX 
THE CHROMOSOMES AND MITOCHONDRIA OF 
GERM CELLS 
No account of the germ-cell cycle in animals can be 
considered complete without at least a brief reference 
to the history of the chromosomes and mitochondria 
of germ cells. The chromosomes have for many 
years been recognized as the most important visible 
bodies in the cell, and their behavior during the germ- 
cell cycle has convinced most zodlogists that they 
may also be regarded as the bearers of hereditary 
factors. The mitochondria, on the other hand, 
are cellular constituents which have only compara- 
tively recently come into prominence in cytological 
literature, and ideas concerning their nature and 
functions are still in a very chaotic condition. 
Tue CHROMOSOME CYCLE IN ANIMALS 
A few general statements regarding the behavior of 
the chromosomes during cell division, maturation, 
and fertilization are contained in Chapters I and II. 
We may recognize a rather definite chromosome cycle 
as a part of the germ-cell cycle, and it is to certain 
events in this chromosome cycle that our attention 
will be directed in the following paragraphs. It is 
best to begin our discussion, as in the general review 
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