130 PARASITOLOGY. 
was not distended and the coagulum, was slightly 
larger than a pea and contained three worms. One 
proved to be a Triodontophorus serratus, the posterior 
extremity of which is illustrated in figure 21, Plate 10. 
The large intestines of this young horse contained 
only two species, those of the Triodontophorus serra- 
tus and the Sclerostomum vulgare. All other worms 
examined up to this time for classification from throm- 
bi and aneurisms have proven to be the Sclerostomum 
equinum. (Strongylus armatus.) One investigator 
has ventured the opinion that this latter parasite prob- 
ably passes its larval stage in the abdominal blood 
vessels. 
THROMBOSIS AND EMBOLISM. 
In those vessels containing small thrombi and which 
must be regarded as rather recent invasions there is 
noted an endarteritis with possibly some destruction 
of the endothelium. Later stages show atheromatous 
changes and in old aneurisms even areas of calcifica- 
tion. The middle coat shows hypertrophy and inflam- 
matory processes. The outer coat shows connective 
tissue proliferation, 
A vessel wall thus diseased may give way to a more 
or less extent and sacculation occurs. The aneurism 
now developed may be saccular, fusiform or cylin- 
droid. On the inner side will be found a mass of 
coagulum adhering closely to the degenerating vessel 
wall. The larvae may be found in the coagulum with 
one end extending out into the blood stream or lodged 
in the walls between the coats or penetrating partially 
protruding on either side of the vessel wall. 
