536 The Philippine Journal of Science 1922 
often turning completely around; finally, the egg splits, freeing 
it. Cort believes that the splitting is not caused by the activity 
of the embryo, but the action of water, and quotes Smith as 
saying that the process of expansion takes place at about 30° 
C. in from ten to twenty hours. 
Miyura and Sudzuki(29) demonstrated that the free-swimming 
animalcule penetrates its intermediate host, Blanfordia noso- 
phora (a kind of sharply conical, dark gray snail, with a dextral 
opening and with seven or eight coils), by dissolving its cuticle 
and neutralizing the secretions of the host with the secretion 
of its own cephalic glands. Once it has gained entrance, it 
makes its way to the gills and wall of the alimentary canal 
where in twelve days the first radie appear. Gradually these 
concentrate in the bile ducts, where they grow and form sec- 
ondary radiz, or the sporocysts of Leiper. When fully devel- 
oped the cercarize escape from the snail and penetrate the skin 
of the vertebrate host (which in his case were mice), causing 
the disease schistosomiasis. 
The anatomical structure and locomotion of both miracidium 
and cercaria are splendidly described by Cort.(6) The mode 
of penetration through the skin is described by him as follows: 
The cercaria takes hold with the ventral sucker and, by ex- 
tending its body and by butting with the spines of the tips 
arranged around the openings of the ducts of the cephalic 
glands, produces a slight opening. Aided by the cytolytic and 
neutralizing secretions of these glands, and by the backward- 
pointing spines, the cercaria is able to penetrate the host. 
Once inside, the cephalic glands and :the tail degenerate. At 
this stage, the sexes cannot be distinguished. 
Miyagawa and Takemoto(28) trace the worms making their 
way into the lymphatic spaces; for the most part they invade 
the blood capillaries or the small peripheral veins, later ac- 
cumulating in the right side of the heart. From the skin they 
may pass through the lymph vessels to the lymphatic glands 
in which many are arrested and killed. The worms that enter 
into the peripheral veins reach the right side of the heart and 
pass directly to the lungs, where they are arrested for a short 
time because of their size. Finally, they return to the left side 
of the heart, pass into the aorta, and are distributed to the 
gastrointestinal canal and from here to the liver through the 
mesenteric veins, or else directly from the aorta into the liver 
by the hepatic artery. The latter route would place the worms 
