=Verminous Aneurisms.= These are perhaps the most important lesions caused by the sclerostome as they are the steppingstone to the dangerous embolisms, and too often fatal colics and congestions of the intestines. They are very common in some localities, and rare in others following the distribution of the sclerostomata. Bollinger found them in 90 to 94 per cent. of adult horses, and Ellenberger in 84 out of 85 horses dissected. They are found in all ages from six months up, and are nearly always in the short, stubby trunk of the anterior mesenteric artery. Often two or three exist in the same animal, the whole length of the posterior aorta showing patches of disease, exudations, neoplastic elevations alternating with depressions, and aneurisms and thrombosis in its different branches. In 100 horses Bollinger found 168 aneurisms, 153 in the anterior mesenteric, and its divisions, 4 in the cœliac axis and its divisions, 3 in the hepatic artery, 3 in the posterior mesenteric artery, 3 in the renal arteries and 2 in the posterior aorta. The special predisposition of the anterior mesenteric artery is variously accounted for: 1st. There is the obvious fact that its branches are distributed to the cæcum and double colon, the home of the mature parasite, and to the small intestines which are first reached by the young parasites that are taken in with the water and the food. These are therefore most likely to get into the branches of this vessel and to follow them up toward its origin. 2nd. The anterior mesenteric artery distributes its branches to the small intestines the most motile portion of the intestinal tract, and the cæcum and colon the most heavily loaded with solid ingesta, it is therefore the most subject to traction, and distensions, and the more so that the parent trunk is extremely short and the divisions pass in all directions and to a large extent at right angles, so that there is a dragging of the walls apart as well as an obstruction to the blood flow and an increase of internal tension. The distension, laceration, inflammation and softening of the internal coat have accordingly been regarded as the starting point of an endarteritis upon which the parasites have been implanted as a further cause of trouble. We must not forget, however, that the sharp circle of teeth of the parasite, by which it fixes itself on the intima of the vessel are quite enough to produce initial endarteritis, without any assistance from distension, traction or laceration.