396 K. MASUI: 
compelled us to admit the following facts: 1. In the early leptotene stage 
some of the chromosomes already begin to unite with their free ends. 2. 
Sometimes in these chromatin threads a longitudinal split appears, but in the 
synaptene stage the conjugated point ‘of two’ chromosomes can not be 
seen. 
JORDAN (711) in opossum has indicated that in the synaptene stage (Fig. 16) 
most of the loops are nearly the height of the nuclear diameter, and the 
summits, of the loops are marked by more compact chromatic knobs, the point 
of union of two threads. In cattle such a conjugated point of chromosomes can 
not be seen during the synapsis and the pachytene stage, but a transverse 
constriction of the chromosomes is found at the late prophase. This constric- 
en an tion probably represents the 
conjugated ends of the uni- 
valent chromosomes. 
From the above data it is. 
conceivable that conjugation of 
the chromosomes occurs by 
telosynapsis (end to end con- 
Text-fig. 1. Ciagrammatic representation of synapsis 
and reduction of chromosome. jugation) during the synaptene 
a, synaptene stage; b, pachytene stage; 
e, diplotene stage; d, late prophase; e, 
metaphase of the first reduction division. somes thus formed may be 
stage, and the bivalent chromo- 
separated along the point of conjugation in the reduction division. 
From the acceptance of occurrence of telosynapsis, it is difficult to prove 
the rapid thickening of the spiremes in the pachytene stage, but’ this difficulty 
may be interpreted as follows: The thickening of the spiremes may probably 
be due to the fact that in the synaptene stage the spiremes as well as the 
nucleus grow very rapidly compared with the growth in other stages. 
The longitudinal splits of chromosomes which appear during the late 
prophase of the first spermatocyte are apparently the same as those of the 
spermatogonial chromosomes. If the nature of the longitudinal split of the 
primary spermatocyte is entirely the same as that of the spermatogonia, then 
this longitudinal split is comparable to that of the somatic chromosome, and 
the chromosome united in the synaptic period must be separated in the first 
division. The first division is, therefore, a reducing division. 
