76 JOSE F. NONIDEZ 
the centrosome. This might be accomplished by a rotation of 
the nuclear contents, as described in the early spermatocytes of 
Batracoseps by Janssens (’03, ’05). Such, however, is not the 
case in Blaps; since the mitosome does not move from its place 
of origin and often may be recognized more or less clearly during 
several cell generations, it offers a fixed point of reference. If a 
rotation of the nuclear contents took place, the centrosome 
would always appear in the half of the cell opposite to that con- 
taining the mitosome. Furthermore, no telokinetic movements 
of the nucleus were observed, as the figures show; even if the 
nucleus turned around the centrosome (the latter retaining its 
primitive position), the apices of the loops would still be directed 
toward the centrosome. 
IV. THE SPERMATOCYTES 
1. The maturation mitoses 
The first maturation mitosis ts reductional for the X-complex. 
In the course of the two maturation divisions the bivalent eu- 
chromosomes, as usual, divide along two planes cutting each 
other at an angle of 90° and their transverse fission takes place 
in the first mitosis. It seems likely that the latter segregates 
two homologous chromosomes, paired during synapsis and placed 
end to end in the metaphase, but we lack conclusive proof of this 
conclusion. The absence of conspicuous tetrads makes very un- 
certain the recognition of the spacial relation of the chromatids 
in each pair, and this is more important than the direction of 
the plane along which division takes place. The fact that the 
X-complex undergoes dissociation during the first mitosis does 
not prove the reductional character of this division for the eu- 
.chromosomes, since several cases have been described in which 
the behavior of the sex chromosomes differs in this respect. 
A. First maturation mitosis. Prophase. At the end of the 
prophase, when the condensation of the chromosomes makes 
possible their certain recognition as separate individuals, these 
bodies may be grouped in two sets, one represented by the large 
X-complex (fig. 86, b), the other by fifteen bivalent euchromo- 
