WENRICH: SPERMATOGENESIS OF PHRYNOTETTIX MAGNUS. 93 
the proximal ends separating and moving about 90 degrees apart, so 
that a rod-shaped element is formed the middle of which represents 
the distal end of the original segment. The rod, thus extended, be- 
comes oriented with its long axis parallel to that of the spindle and it 
separates in the middle, thus bringing about an equational division. 
Tetrad “A” also forms rings, but these were not traced into the meta- 
phase, and their later behavior is not known. 
4. Tetrad “B” occurs in one or the other of two forms: either (1) 
as an equal pair (in two of the thirteen animals), or (2) as an unequal 
pair (in the other eleven animals). The unequal pair differs from the 
equal in the absence of a large terminal granule at the distal end of 
one of its members. Both types show the same behavior, opening 
out at both ends of the segment so that a cross is formed. The 
separation along the plane of the primary split is the greater and occurs 
at the distal end; but the cross becomes so oriented on the spindle 
that the short arms (i. e. the proximal end of the original segment) are | 
attached to the spindle-fibers. Separation in metaphase is therefore 
along the plane of the secondary split, thus constituting an equational 
division. 
5. Tetrad “C” occurs in three forms, designated Ci, C2 and C3. 
C; is composed of very unequal elements, the larger of which possesses 
a relatively very large terminal knob or granule that is not present 
on the other. C, is a pair with equal members each of which appear 
to be homologous to the smaller member of C;. C3 is a pair of unequal 
elements neither member of which appears to be exactly homologous 
to the components of C, and C:. The smaller member resembles 
those of Cz and may be homologous to them. The larger member is 
midway in size between the two members of C;. C2 and C3 divide 
equationally in the first maturation mitosis, but C, divides half the 
time equationally and half the time reductionally in this first division. 
When dividing reductionally the two unequal dyads follow the law of 
chance in their distribution with reference to the accessory chromo- 
some, which passes to one pole undivided. 
6. Study of the early growth-stages of the first spermatocyte shows 
that each of the chromosomes of the telophase of the last sperma- 
togonial division forms a long spirally coiled thread, which uncoils 
and stretches out to form the leptotene threads of the primary sperma- 
tocyte. The leptotene threads conjugate side-by-side (parasynapsis) 
to form the double threads of the pachytene stage. 
7. It was possible to recognize the chromosome-pair A in the 
spermatogonia as two separate chromosomes (telophases) and to 
