70 JOSE F. NONIDEZ 
complex. In both papers, however, conflicting results were 
reached with reference to the number of chromosomes and the 
composition of the X-complex in B. lusitanica, which seemed to 
be variable even in the same individual. It was soon realized 
that these conflicting results were due to imperfect observation 
rather than to differences in the process of reduction and that 
further study was needed in order to solve the question. 
The present paper is the result of a new investigation of the 
whole subject, including the reduction of the chromosomes and 
especially the origin and behavior of the X-complex. The re- 
Spermatogonia ** Maturation Mitosis 2nd Mitosis 
a 7 
Metaphase Anaphase 92 0 
30+5 15 biv.+5 ee 9 15+4 
Are 
re) O DE —" ~ 090 
O 
a 09% Wolo We 
Sei. OES Oo eee 
IEA RO) oy SOX@ 
oO Ss 
oak LS J 15+1 
Diagram 1 
sults described in the following pages agree, in the main, with 
those recorded in my previous papers, so far as the features of 
reduction are concerned, but the conflicting results on the com- 
position of the complex have been cleared up and the conditions 
upon which the doubts were based carefully compared. I have 
been fortunate in obtaining a series in which the true composi- 
tion of the complex could no longer be doubted, since its com- 
ponents are most clearly shown. 
Briefly stated, in the spermatogonial mitoses of B. lusitanica 
thirty-five chromosomes occur, three of which are remarkably 
large (diagram 1). During synapsis the three large chromosomes 
and two of the smaller (represented in black in the diagram) 
