308 WHEELER. [Vion; Tif. 
structed from a series of isolated observations. While the yolk 
is accumulating, the nucleus becomes amceboid, leaves its posi- 
tion at the centre of the egg, and travels to the surface. The 
egg is at this time very slightly curved, and the nucleus always 
passes to the centre of the concave side. This ameeboid 
nucleus is seen in Fig. 6 just after reaching the surface. It is 
still large, and does not stain more deeply than the surrounding 
yolk bodies. Its long axis:is parallel to the long axis of the 
egg. The chromatin, in large masses in the younger egg, has 
been reduced to numerous granules of varying size, still recog- 
nizable as chromatin because staining deeply in borax carmine. 
The pseudopodia are now drawn in, and the nucleus becomes 
spheroidal. Soon the face in contact with the surface becomes 
cup-shaped, and round masses of a homogeneous substance indis- 
tinguishable from the surrounding yolk bodies fill the cavity 
(Figs. 7 and 8 4). In this stage the nucleus is probably giving 
off the “maturation spheres” (Reifungsballen), which Stuhlmann 
saw given off from the nucleus of so many insects’ eggs (notably 
Lepidoptera) ; Will (51) also describes this process in Hemiptera. 
In many insects Stuhlmann found that these spheres differed 
from the surrounding yolk bodies in power of refraction, etc. 
The concavity (Einbuchtung) of the nucleus in A/atta often 
contains several of these spheres. Figure 8 represents such a 
nucleus seen from the surface, the plane of section being at 
right angles to the plane of section in Figs. 6 and 7. Here the 
concavity is composed of separate cavities which have fused. 
The maturation spheres, after their escape from the nucleus, 
mingle with the yolk bodies. Above the orifice in Fig. 8, 
at pu, is a small body, denser and more refractive than the 
surrounding plasma. I think it corresponds to Stuhlmann’s 
paranucleolus. In its centre is a deep red body, probably a 
granule of chromatin. In Fig. 9 is seen a nucleus containing two 
paranucleoli, pz, destitute of the central granule. I cannot say 
what becomes of these bodies. They do not appear in all nuclei 
(confer Fig. 7), and are probably evanescent structures formed 
and again disintegrated during the mysterious process of nuclear 
degeneration. In Fig. 9 granules of chromatin, most numerous 
near the point x, are scattered through the karyoplasm. The 
disintegration of the nucleus by giving off the maturation 
spheres progresses till, when the egg is about 2 mm. long, it is 
