118 W. R. B. ROBERTSON 
3. ON SYNAPSIS AND REDUCTION 
In their behavior these unequal tetrads throw a good deal of 
light on the nature of the synapsis of chromosomes and their 
separation from each other in the reduction division. In regard 
to the beginning of this process, the individuals furnishing these 
abnormal chromosomes do not have much to show, as I have 
said above. This beginning, however, I determined from normal 
spermatogenesis, and have worked it out in my second paper. 
I have found the pairing process in the Tettigidae to start as 
a parasynapsis and to end in a telosynapsis (end-to-end pair- 
ing). In the synizesis period following the last spermatogonial 
division, the members of each pair of chromosomes, six pairs 
in all, having assumed the thread condition, are seen to arrange 
themselves in side-by-side fashion. The number of threads is 
at first twelve, in addition to the accessory chromosome. The 
twelve threads are seen to become six double and finally six single 
threads. During this period the sex chromosome usually lies 
at one side of the nucleus. This condition of pairing continues 
into the later growth period, when the members of each pair 
move apart, the separation beginning first at the proximal ends 
(figs. A, to A,), the chromosomes of a pair remaining attached 
to each other at the distal ends (figs. Ay, A;). Each rotates 
through 90° and the two then form a rod (fig. As), which may 
show, by a slight constriction, the point of contact of the two 
members. In this condition the paired chromosomes (tetrads) 
enter upon the first maturation division. 
In the behavior of these unequal pairs I feel perfectly certain 
that the same thing must have taken place, for I see no reason 
to think that these abnormal pairs should behave differently 
from the normal chromosomes during this process. Their 
behavior on the maturation spindle and in the anaphase follow- 
ing is in every way similar to that of the normal chromosomes, 
and we have every reason to believe that a parasynapsis ending 
in a telosynapsis has taken place. The unequal pairs appear 
on the maturation spindle in the telosynapsis condition. 
Attention, first of all, should be called to the permanency of 
size of these abnormal pairs, especially of the abnormal members 
