ACCOUNT OF THE GERM-CELL CYCLE 43 
tion, and as shown in Fig. 9 these divisions result 
in the production of four functional spermatozoa 
in the male, and one functional egg and three polar 
bodies (abortive eggs) in the female. This increase 
in the number of cells is not, however, the most im- 
portant phase of the maturation process, since a 
large part of our knowledge of the physical basis of 
heredity has been derived from studies of the be- 
havior of the chromatin at this time. This subject 
will be dealt with more fully in Chapter IX, and 
for the present only a brief account of events need 
be given. 
The first thing to be noted is that the mitoses 
leading to the division of the germ cells during mat- 
uration differ from those of ordinary cell multiplica- 
tion. The germ cells, when they are ready for the 
maturation divisions, are known as primary odcytes 
and primary spermatocytes. The nuclei of these 
cells possess the complete or diploid number of 
chromosomes, characteristic of somatic cells; but 
after maturation the eggs and spermatozoa con- 
tain only one-half of the original diploid number, 
or the haploid number. These mitoses are conse- 
quently called reducing or meiotic. The details of 
these mitoses differ in male and female germ cells 
and in different species of animals. 
During and at the close of the growth period in the 
male the chromatin granules form a spireme which 
condenses at one side of the nucleus, a condition 
known as synizesis. After a time the spireme 
again spreads throughout the nucleus, but is now 
