J. jS, BLOOMFIELD. 
Si 
24, 25) ; but a not uncommon form is that with six, which is 
to be regarded as abnormal. 
It is in this stage that there is first any indication that, as the 
spermatoblasts are being formed, a slight quantity of protoplasm 
is being left in the centre of the generating polyplast, which, as 
development proceeds, will form a cushion on which the sperm 
rods may rest. It is best seen in polyplasts which have been 
subjected to pressure, when the filament- cells or spermatoblasts 
will be squeezed asunder, but remain connected with the central 
substance by fine strands of protopalsm (fig. 26). This central 
mass is the ^ blastophor.' 
The general outline of the eight-divided cell is circular, but 
often oval. 
The following stages up to the appearance of the complete sper- 
matozoa may be made out in a preparation of a well-developed 
seminal reservoir from a large worm. The youngest stage in 
such a preparation is a flattened, oval, plate-like corpuscle, which, 
in the fresh state, appears to be composed of finely granular 
protoplasm, with very slight indications of the several spermato- 
blasts of which it consists, except a curious vacuolation, which, 
having a radiate direction, seems to mark the separate cells 
(fig. 29) . These corpuscles are highly refractive, and have sharp, 
w'ell-defined outlines. On treatment with acetic acid, or the 
mode recommended above, these corpyiscles become broken up 
into their component spermatoblasts. Besides these, in the fresh 
state occur others, in which the component cells are more distinct, 
owing to projecting pieces of protoplasm, which give them an 
angular appearance. 
It is not possible to determine accurately the number of sperma- 
toblasts which form one of these corpuscles, as only one side is pre- 
sented to view, but it probably varies from sixteen to sixty-four, 
or more. Viewed in optical section laterally, the spermatoblasts 
are seen to be placed on a central mass of protoplasm — the sperm- 
blastophor, w^hich is flat (fig. 29), in accordance ^ with the 
flattened shape of the whole corpuscle. These flattened plate- 
like forms have arisen by division of the nucleus from the 
primitive phase of the spermatospore, w^hich was a single nucleated 
cell. Though the primitive cell was spherical, yet, after its first 
division, when there are two nuclei and two cells, it is oblong 
and flattened ; the quadripartite form is flattened, and so is the 
one with eight divisions, or nearly so, as it is possible in these 
stages to count the component cells. 
The most interesting point in this stage is the division of the 
whole s})ermatosphere. In the fresh state the indication of this 
division is very conspicuous, and as the component spermatoblasts 
are not distinguishable, it looks as if one large cell were under- 
