46 
Bilharziasis 
The difference in the two species Schistosomum haematobium and Schisto- 
somum mansoni is enumerated in detail in Table III, which has been con¬ 
structed after a careful study of the morphology of these two schistosomes. 
Table III. 
Differences observed in the two species of Schistosomum. (Text-figs. 1 and 2.) 
S. haematobium (Bilh. v. Sieb. 1852). (Fig. 1) 
Male 
Length 1-5 cm. 
Finely tuberculatecl. 
Testes large and generally four in num¬ 
ber, posterior to ventral sucker. 
Female 
Length 2 cm. 
Ovary in posterior third of worm, in 
front of intestinal caeca. 
Uterus contains large numbers of ter¬ 
minal spined ova with spine directed 
backwards (maximum numbei 50). 
Lateral branches of intestinal canal 
unite in posterior third. 
Yolk glands distributed in posterior 
fourth of the body. 
S. mansoni (Sambon, 1907). (Fig. 2) 
Male 
On the average slightly shorter than 
S. haematobium, about 1 cm. 
Grossly tuberculated. 
Testes small and eight in number, pos¬ 
terior to ventral sucker. Ventral 
sucker more prominent. 
Female 
Length 1-5 cm. maximum. 
Ovarv in anterior half of bodv, in front 
of union of intestinal caeca. 
Uterus contains usually one, at most a 
few, lateral spined ova, with spine 
directed backwards. 
The lateral branches of the intestinal 
canal unite in the anterior half of the 
worm. 
The yolk glands are widely distributed 
in posterior half of the body. 
Note. From available literature it appears that worms of S. japonicum are of smaller size, the 
male being from 0-9 to 1 -2 cm. long, and the female 1-2 cm. long, though Katsurada (1913) has de¬ 
scribed specimens 2 cm. and over. The ventral, relative to the oral sucker, is proportionally larger. 
The integument of the male is smooth, and non-tuberculated. The posterior part of the body is 
relatively wider, the over-lapping of the gynaecophoric canal being more extensive than in the 
other schistosomes. 
The Habitat of the Adult Worms in the Veins, and the 
Method of Deposition of Ova in the Tissues. 
These observations were made on the adults of S. mansoni and S. haema¬ 
tobium lying in the mesenteric veins of anaesthetized monkeys. 
The coupled worms, males and females, lying in the loops of the mesenteric 
veins, make their way to the finer venules, progressing by means of peristaltic 
movements of the body, and by action of the ventral sucker. The male assumes 
the chief part in this progress, the female being carried in a purely mechanical 
manner, in the gynaecophoric canal. Quite often, bunches of six or more 
coupled worms are seen progressing in one large vein in this manner. 
The male adheres to the vessel wall, first by its ventral sucker, then by 
muscular contraction, the head lengthens out and a new grasp is obtained 
of the vessel wall. The anterior sucker does not appear to be used as an organ 
