WENRICH: SPERMATOGENESIS OF PHRYNOTETTIX MAGNUS. 69 
the plane of the primary split is never completed, but that the chroma- 
tids again become separated at the proximal end, assuming the forms 
shown at f to 2, figure 62, and that the first division is therefore always 
equational. However, the possibility of an occasional reductional 
division as a result of the ring-formation must be taken into eonsidera- 
tion. ‘pu 
2. Chromosome-pair B. Figure 63 (Plate 6) presents a series of 
stages for B corresponding to those in figure 62 for A. This series of 
stages of B supports the conclusions reached from a study of A in 
regard to:— (1) a probable parallel association in the pachytene 
stages of pairs of threads, each representing individual chromosomes; 
(2) the formation of the tetrad by, first, a separation along the plane 
of conjugation (7. e., the primary longitudinal split) and, secondly, 
by a splitting of each of the original conjugants (the secondary longi- 
tudinal split); and (3), as a result, an equational division of the tetrads 
at the first division. 
This chromosome-pair (B) is characterized by the presence of large 
and well-marked polar granules at both ends and by a similar large 
granule not far from the middle, though always somewhat nearer the 
distal end. Leaving aside the formation of rings, the chief difference 
in behavior between A and B is that in the former the plane along 
which the greatest separation takes place before metaphase is that of 
the secondary longitudinal split, while in the latter the greatest separa- 
tion takes place along the plane of the primary split. This results 
in A becoming extended in the direction of the spindle-axis, as already 
described, while B becomes extended at right angles to this axis. In 
the latter case the separation along the plane of the primary split does 
not become complete at the expense of the separation along the plane 
of the secondary split, but the latter separation persists for a short 
distance, giving rise to a cross with unequal arms (fig. 63, g, h). The 
short arms terminate in the proximal or synaptic ends of the chroma- 
tids, while the longer arms terminate in the distal ends. 
However, these differences in behavior between A and B are not 
fundamental, since the final result, an equational division, is the same 
in both cases. But they are indications of the individual peculiarities 
of these elements. It should also be pointed out that such differences 
could easily be misinterpreted, if only parts of the histories of the 
pairs were known. 
It is important to note that the drawings of the series shown in 
figure 63 were all taken from sections of a single testis. In searching 
for the same element in other individuals, I was surprised to find the 
