306 WHEELER. [Vo. III. 
of translucent polyhedra, is a pre-arrangement for the reception 
of the blastoderm, and more particularly the future embryo. 
The vital activities, which, in forming the embryo, finally be- 
come centred on the ventral face of the egg, find the yolk here — 
already sufficiently decomposed to admit of easy metabolism into 
protoplasm. Later, in eggs with advanced embryos on their 
ventral faces, the granular yolk has again become transparent 
and homogeneous in extensive masses which arise from the con- 
fluence of many of the polyhedral bodies. I differ from Bloch- 
mann in maintaining that the granular yolk is originally derived 
from the homogeneous variety. He was led to infer the oppo- 
site process from his study of the yolk in ants’ eggs. 
Protoplasm.—In young ovarian eggs, 0.25 to 0.5 mm long, 
the cytoplasm is finely granular. The deutoplasm begins to 
accumulate, and by the time the egg has become 1 mm long, 
the above-described vitelline bodies and oil globules have de- 
veloped in such numbers as to reduce the protoplasm to an 
exceedingly delicate net. In the mature egg the Kezmhaut 
described for so many insects’ eggs is a layer so thin that it is 
just perceptible on the centre of the dorsal surface and at 
the cephalic pole (Fig. 4 gv). This protoplasmic layer is full of 
what I shall call Blochmann’s corpuscles. They are minute rod- 
shaped bodies so numerous in the surface protoplasm as to make 
it appear reticulate. They Jook like bacillar micro-organisms, 
stain deeply, and according to Blochmann, who is probably right 
in thinking that they play an important role in the development 
of the egg, multiply by transverse division (like Bacteria). 
Weismann was the first to note these bodies in Diptera in 1863.’ 
Blochmann (3, 4,) called attention to them in 1884 and 1886, in 
the eggs of Camponotus and Formica, and in 1887 in Llatta, Peri- 
planeta, Pieris, Musca, and Vespa. In the three last genera the 
bodies are spherical. In several of Stuhlmann’s (45) figures, 
these bodies are prominent. In &/atta I have found them wher- 
ever the peripheral layer of protoplasm is perceptibly thickened, 
especially surrounding the polar globules on the middle of the 
dorsal surface (Figs. 14, 15, and 16), and at the cephalic end of the 
egg (Fig 4 77). They seem to be made of more rigid material 
than the protoplasm in which they are embedded, for they pro- 
trude as very minute prickles from the surfaces of eggs hardened 
in Perenyi’s fluid. I have not been able to trace out their der- 
ivation and ultimate destiny. 
