CYTOLOGY OF ANISOLABIS MARITIMA BON. 
241 
spermatogonial division. Here there is seen a double, rather 
angular body (xx), and a deeply staining sphere (y). With the 
establishment of the leptotene threads (Plate XXV, fig. 18), the 
xx-and the y-element come into close apposition and remain 
connected, sometimes merely by a small strand (Plate XXV, 
figs. 19, 20), and also during syndesis they continue this connec- 
tion. When the zygotene threads are well formed, the xx- 
element separates from the y-element. Often they come to lie 
at some distance from each other in the nucleus, but apparently 
not under control of the centrosome at the positive pole of the 
nucleus (Plate XXV, figs. 21, 22). 
With the beginning of the strepsinema the xx-element and the 
y-element again approach each other and are again connected 
by a narrow strand (Plate XXV, figs. 23, 24). The xx-element 
reveals its two-fold constitution, when viewed at a favorable 
angle in well-decolorized haematoxylin preparations, and es- 
pecially well in crystal violet + alizarin slides. At the establish- 
ment of the strepsistene stage we notice the coalescence of the 
xx-and the y-element. In iron-haematoxylin the y-element has 
a lighter cortical zone, and a more deeply stained center. The 
doubleness of the x-portion is no longer so distinct (Plate XXV, 
figs. 25-26). 
When the autosomal tetrads are formed, but are still very 
granular, there appears on the xxy-complex a highly refractive 
spherule (fig. 27, nl), which separates from its parent mass at 
about the time the smooth, deeply staining tetrads are estab- 
lished. This nucleolar body may then lie anywhere in the nucleus, 
even in close appostion to one of the autosomal tetrads. As 
the centrosome divides and preparation is made for the first matu- 
ration spindle, this nucleolar body diminishes in size and finally 
disappears, leaving eleven autosomal tetrads and the xxy-hexad 
to enter the metaphase plate. 
Not only form but also differential reaction to stains enables 
one to trace the evolution of the hexad. In safranin + lichtgriin, 
the y-element is not so deep a red as the xx-component, in stages 
corresponding to those shown in figures 17-26. The y-element 
also appears vacuolated, and has a greenish tinge in the early 
