48 
BillLarzi axis 
female from a branch vein leads to a resumption of the blood current which 
impinging successively on the thin anterior ends of the ova drives them through 
the vessel wall into the perivenous tissues. 
In the case of lateral spined ova, the marked increase in the transverse 
diameter of the ovum caused by presence of the lateral spine facilitates it in 
engaging the wall of the vessel (see Text-fig. 3). 
In the case of the terminal spined ovum, unless its long axis lies mathemati¬ 
cally parallel to that of the vessel, the impact of the blood current on its 
anterior end will turn it in an oblique direction. Immediately this occurs, the 
terminal spine will engage the vessel wall, and penetration will follow. 
By these means the adult females reach the submucous tissue and the ova 
appear in the urine or faeces, as the case may be, within a few hours of being 
deposited, unless held up by fibrous tissue. 
The description set forth above is not based on theory but upon the follow¬ 
ing observations: 
(i) The female worm is often found separate from the male on opening 
the abdomen of an infested monkey under anaesthesia. 
(ii) The female worms may be found singly in microscopic sections, filling 
up the veins of a calibre approximately equal to their own. 
(iii) Direct microscopic examination of pieces of the intestine (of infested 
monkeys), squeezed between glass slides by means of rubber bands, will 
reveal the presence of ova in the vessels. Generally, several ova are deposited 
in a single vessel at close intervals. In many cases the diameter of this vessel 
is no larger than the transverse diameter of an ovum, and indeed, is often less, 
so that the vessel may present the appearance of a string of sausages. In some 
vessels ova could be observed lying in close apposition to the vessel walls, but 
without the spine having engaged. In others, the spines, both terminal and 
lateral, could be seen projecting through the vessel walls, while the bodies of 
the ova still occupied the lumen. In other cases ova could be observed lying 
free in the tissues outside the ruptured venule. The ova were always lying in 
the vessel with the anterior blunt end pointing in the direction of the decreasing 
diameter of the vessel, and with the spines in the direction of the portal blood 
current. 
(iv) By means of a hand lens sacculations of the vessel walls could be 
observed corresponding with the long strings of ova referred to. 
(v) Examination of the uterus of gravid females has revealed the ova 
in situ , and invariably they are placed with the spine, whether lateral or 
terminal, posteriorly, and the blunt narrow end of the ovum, anteriorly 
situated. 
