IV. THE FORMATION OF THE OOCYST 
After the fertilisation of the female gametes the male half of the 
cephalont degenerates, and the female portion grows until it fills the 
whole cell, which then separates from its attachment to the stomach 
wall and becomes free in the cavity. Each female gamete grows 
in size after fertilisation, while the fibrous cell-wall thins with the 
distension. The gametes, or zygotes as they must now be called, are 
highly refractile bodies, each about the size of a red-blood corpuscle. 
They are packed tightly in the fibrous capsule or sporocyst, which 
resembles a pomegranate that has been cut through the middle with 
a sharp knife. It is about fifty times the size of a stomach cell, and 
if the stomach wall be ruptured it may' be extruded, transferred to a 
clean slide, burst, stained and examined. But under natural 
conditions it passes down to the pydorus, through which it is too large 
to move, and it ruptures, and the contained zy'gotes escape into the 
intestines (Malpighian tubes) under tlie influence of the peristaltic 
action. 
V. THE DEVELOPMENT OF THE SPOROBLASTS 
If a cyst be expressed from the stomach, crushed on a slide, and 
the sporoblasts stained by any method giving the Romanowski result, 
they will be found to be lanceolate in shape but of somewhat irregular 
contour. Each one has some chromatin, but this varies in amount 
from a minute dot to an extensive streak. The cell-wall is glistening, 
and appears almost chitinous, while there is some very feebly staining 
cytoplasm. But they have a high osmotic index, for if the intestine 
containing them be placed unruptured upon agar spread on a glass 
slide and containing polychrome methylene blue, according to the 
method described in the Journal of Physiology, for September i6th, 
1908, by H. C. Ross, it will be noticed that the living sporoblasts 
accept the stain before the cells forming the lining to the tube. But 
even these cells accept the stain more readily than the hepatic cells, 
or the epithelial cells of the stomach or of the salivary glands. They 
ai-c therefore, l ery susceptible to external influences. 
After the cyst has ruptured the sporoblasts pass into the 
intestine, where they undergo a still further change. They become 
barrel-sliaped sporocysts; the contour is regular, and in the fresh 
