21,6 Mendoza-Guazon: Schistosomiasis in the Philippines 537 
in the arterial channels of the gastrointestinal tract as well as 
in the venous side, which is in accord with the findings of 
Phalen and Nichols(31) and of Catto. 
The adult male is flat, 9 to 12 millimeters in length by 0.5 
millimeter in breadth. The female is 12 to 26 millimeters in 
length by 0.4 millimeter in breadth, according to Manson. (24) 
Fantham, Stephens, and Theobald(13) give as extreme limits 
5 to 22.5 millimeters and, for the female, up to 26 millimeters. 
The adult males, obtained from autopsy 9132, measure from 
6 to 9 millimeters (Plate 5, fig. 2), and one of the females 
measures 20 millimeters (Plate 5, fig. 1). The females are 
longer and thinner than the males. The middle portion of the 
female is thicker than the anterior or the posterior, and the 
surface is smooth. The oral sucker is smaller than the ventral, 
and both are armed with fine spines. The uterine canal is 
straight, commences as a little pouch about the middle of the 
body, and ends in a point below the ventral sucker. The ova 
at this place are in pairs and have their long axes parallel to 
the long axis of the uterine canal. There is a slight constric- 
tion of the canal between the four pairs of ova so that they 
look like coffee beans, as they are flat on the line of apposition. 
The next ova have their long axes diagonal to the axis of the 
canal. Below them there is a slight constriction of the canal 
and the portion posterior to this is more dilated than that above 
or anterior to it. The ova in this dilated portion look larger, 
have their long axes either parallel or diagonal to the axis 
of the canal, and lower down they are in twos or threes, and 
in various positions. About the middle of the body or a little 
below, the elliptical ovary is well marked with its pointed end 
anterior. The large end is posterior and from this a tube winds 
upward to join the end of the uterus. Another tube, which 
is thicker than the one mentioned, runs downward into the 
branched vitellarium. The junction of these tubes with the 
uterus is partly covered from view by the clear racemose shell 
gland. The habitat of the worms, according to Manson, (24) 
is the smaller mesenteric blood vessels, especially those drain- 
ing the large intestine. Immature ones may be present in the 
portal and splenic veins, also in the gastric veins and in the 
coats of the small intestines, and even in the coronary veins 
ef the heart. In this series, the adults were found in the 
portal vein of the liver in the first case, and in the tenth case 
in the portal vein and in the branches of the splenic vein. © 
