362 K. MASUI: 
As stated before, it is not possible to make out the individual chromosomes 
during the prophase, since they overlie one another, but among the curved 
chromosomes an oval or heart-shaped accessory chromosome can be found 
which usually takes its position at a point outside the ordinary chromosomes 
(Figs. 29, 30). This odd chromosome can be identified by its shape and 
behavior in all the succeeding stages of first reduction division. In the final 
prophase the chromatoid corpuscles are always situated among the chromosomes 
(Fig. 30) but can be easily distinguished from the latter by their small size. 
Finally the mitochondria become scattered throughout the cell body in this 
stage. 
B. Tue First Repucrion Division. 
The number of chromosomes :—As in the case of the spermatogonia, the 
chromosomes also have a tendency to mass together in the metaphase plate 
of the first reduction division. On account of their haploid number and 
largeness in size, it is not, however, difficult to distinguish them individually 
and so to count their number. For this investigation preparations which are 
stained with iron-haematoxylin and FLEMMING’S triple dyes are used. With 
iron-haematoxylin it is necessary to decolorize the preparation strongly, as 
otherwise the boundaries of the chromosomes can not be distinguished. Careful 
examination of good polar views of the spindles of more than fifty preparations 
of the first reduction division convinced me of the presence of eighteen chromo- 
somes in the equatorial plate in one half of them and nineteen in the other 
half (Figs. 32—36). This difference in number is to be accounted for by the 
presence or the absence of the accessory chromosome in the one or the other. 
In those cells in which nineteen chromosomes are found we have eighteen 
bivalent and one univalent accessory chromosome (Figs. 35, 36). 
Besides, the chromosomes show distinct and constant differences in size. 
In those cells in which eighteen chromosomes are counted, we can distinguish 
four large-, ten middle- and four small-sized ones (Text-fig. 1 6). In the other 
halt number of the cells which contain nineteen chromosomes we have four 
large-, eleven middle- and four small-sized ones (Text-fig. 1 a). Thus it is 
one of the eleven middle-sized chromosomes, that is to be accounted for as an 
ACCESSOLY. 
