176 Schrader. 
and comes to the following suggestive conclusions: In this case the 
symbionts are not dissociated from the accompanying cells before 
entering the egg. These cells are however later replaced by other 
cells derived from the developing embryo, and disappear. BUCHNER is 
uncertain as to the exact origin of these cells, but is positive that they 
are not early cleavage cells. 
PIERANTONI and SHINJI both observed the association of cells 
with the symbionts, but differ from each other as well as from my 
account in these interpretations. PIERANTONI (1910 and 1913) believes 
that the cells are nothing but early cleavage cells, which become 
associated with the symbionts accidentally. That PIERANTONI saw 
cleavage cells among the symbionts, I do not doubt. They can be found 
there in every egg which shows the cleavage cells migrating to the 
periphery, and I can agree with him therefore in believing their pre- 
sence there to be accidental. But certainly this association is not a 
permanent one, and the cleavage cells involved soon drift between and 
away from the symbiont spheres toward the periphery. SHINJI (1919) 
does not mention the cleavage cells in this connection and seems to 
have been unaware of PIERANTONTSs investigations. But as has been 
said, he also noted the association of cells with the symbionts. His 
account of the embryology in coccids, which I will consider in this 
connection, suffers in clarity because of the fact that his drawings are 
presented with little regard to order or sequence and that the labelling 
is frequently careless. Moreover his interpretations at times receive but 
scant support from the figures given, but it is not to be forgotten that 
he purports to present nothing but a general account of development. 
Although my own investigation was primarily not intended to 
extend beyond the stages already described, SHINJI’s interpretations 
have made it practically a necessity to carry the work to later phases 
of the embryology. The points in SHINJT’s paper touching on the 
present account are briefly as follows: The germ cells are the first 
cells to be proliferated after the establishment of the blastoderm stage. 
They are large clear cells that arise near the point where the germ 
band begins to form, that is, near the posterior pole. After formation, 
they migrate through the egg to the anterior pole where the symbionts 
are located. Some of them come into close association with the latter, 
penetrating between the spheres and also forming an external envelope 
around the group of spheres. Not all of the primordial germ cells are 
thus involved, however, and a certain number is left outside of the 
