38 
Bilharziasis 
It is covered with cilia, except at the anterior end where a papilla is situated. 
Excretory organs, and round clear germinal cells are both noticeable in the 
body cavity, and two or three transverse constrictions may be noted (while 
the miracidium is still unhatched) as grooves or indentations of the lateral 
borders (Plate I, figs. 1 and 2). On reaching its specific intermediate host, 
the previously enumerated species of Bullinus snail in the case of Schistosomum 
haematobium, and in the case of Schistosomum mansoni, Planorbis boissyi, the 
miracidium gains entrance by boring through the soft tissues, and eventually 
reaches the digestive gland, or liver. 
Here, as previously noted, by proliferation of its germinal cells, the mother 
and daughter sporocysts are formed, and the ultimate development of the 
cercariae takes place in their interior. 
A sporocyst is a simple sac, without either alimentary canal or oral sucker. 
The sporocysts under consideration are elongated finger-like cysts with thin 
walls, thickened at either end. They have independent but feeble power of 
movement, and appear to absorb nourishment directly through their walls. 
Over distension of the daughter cysts leads to rupture, and the evacuation 
of their contents. Where rupture takes place prematurely, we noted the follow¬ 
ing developmental forms: 
(1) Hounded or oval masses of cells. 
(2) Elongated oval masses of cells showing a tendency to form a posterior 
process. 
(3) A shapeless type of cercaria, with a partially developed anterior part, 
and a blunt posterior part—the future tail. The earliest indication of the forked 
nature of the latter is seen in two small buds at its posterior end. 
(4) The fully developed mature cercaria with anterior and lateral suckers, 
and a long bifid tail. 
The above enumerated forms evidently represent the different stages in 
the development of the cercaria from the germinal cells of the sporocyst. The 
enormous development which may take place is shown in Plate V, fig. 1, where 
almost all the normal glandular tissue is displaced by sporocysts. 
Morphology of Cercariae of S. haematobium and S. mansoni. 
The specimens for this purpose were obtained by dissection of the livers 
of infected snails of the species, Planorbis boissyi, and Bullinus contortus and 
dybowski. 
These organs were teased out and the contained cercariae killed by 
heat. The specimens were then examined under a cover-glass. Xo marked 
difference was noted in their internal structure from the description given by 
Leiper in his original paper on the subject and the more recent minute one by 
Faust (1919). In live specimens the movements also correspond. In the main 
points of structure they resemble the cercaria of S. japonicum, as described 
by Ogata (Verb, der Japan, path. Gesellsch. Tokyo, 1914, vol. 48). 
