80 JOSE F. NONIDEZ 
be detected (figs. 42 to 44, 46 to 48, a, 6), but in many meta- 
phases only one of the small chromosomes is seen (figs. 45 and 
48, c), and in others both seem to be absent. 
An unusual form of complex is represented in figures 47 and 
48, b, in which the X-chromosome failed to condense at the be- 
ginning of the growth period and appears as a curved, more or 
less V-shaped body, united at the ends with the M-chromosomes. 
The small chromosomes are easily recognized here, lying at 
slightly different levels and connected with the X-chromosome 
by means of delicate threads. 
Although the preserving fluids used are not the best to show 
clearly the spindle fibers, it was possible to detect their mode of 
attachment to the complex. The normal attachment is seen in 
figure 46, b. One spindle fiber is attached to the X-chromo- 
some, another to one of the M-chromosomes; the other M- 
chromosome and the small chromosomes lack a spindle fiber of 
their own. There are, however, some variations in this respect, 
which will be described later. The euchromosomes possess a 
double attachment, both fibers being attached at their ends so 
that their longer axis is parallel to the axis of the mitotic figure. 
Anaphase. ‘The most interesting feature of the first matura- 
tion mitosis is the distribution of the chromosomes involved in 
the X-complex among the secondary spermatocytes. As shown 
in diagram 1, one of the latter receives four of such chromosomes, 
while the other receives only one. Furthermore, on account of 
the almost constant position of the X-chromosome in the com- 
plex, it was possible to detect its entrance into the spermatocyte 
receiving four chromosomes. In this way two kinds of secondary 
spermatocytes arise, one in which the total number of chromo- 
somes is nineteen—15 euchromosomes plus 4 X-complex com- 
ponents—the other with sixteen chromosomes—15 euchromo- 
somes plus 1 X-complex component. 
This distribution is constant in normal cells, but in a few cases 
the large chromosomes enter the same spermatocyte; there is, 
however, every reason to believe that the latter does not produce 
a functional spermatozoon. The irregularities in the distribu- 
tion of the small chromosomes are of a somewhat wider occur- 
