404 Veterinary Medicine. 



veloped and containing an extraordinary number of ova and free 

 embryos. Ovoviviparous. 



They probably enter the body in food or water and bore their 

 way from the alimentary canal to the dermal and subdermal con- 

 nective tissue. Railliet injected a large number of embryos under 

 the skin of a mare but no morbid result followed, from which it 

 has been inferred that the parasite must pass through earlier 

 stages of development outside the equine body to fit it for the in- 

 ternal habitat. 



Symptoms. The first obvious symptom is the eruption on the 

 skin of groups of nodules, in size from a pea to a hazel-nut, hard, 

 resistant, and painless, surrounded by a slight cedema, and sur- 

 mounted by the erection of the hair in tufts. These nodules ap- 

 pear mainly on the sides of the trunk, but may show on any part 

 of the body or limbs. The eruption, which appears quite sud- 

 denly, is partly the result of exudation, but mainly of the extra- 

 vasation into the surface layers of the derma, and beneath the 

 epidermis. In the centre of the nodule it bursts through the 

 cuticle and dries into a reddish scab around the erect tuft of hairs. 

 The bleeding may occur an hour or two after the formation of the 

 nodule, and the latter promptly subsides, leaving the skin nearly 

 smooth, but for the aherent, dried blood clot. A succession of 

 nodules, however, appear day after day in a group suggesting the 

 successive lesions caused by one or several parasites, in the same 

 situation. The groups of nodules may be kept up for several 

 weeks by successive formations, or they may subside in a few 

 days to reappear after an interval of three or four weeks. They 

 are usually confined to the three or four months of spring, and 

 disappear absolutely in the winter. 



The eruption, however, recurs in the same horse in the follow- 

 ing spring, and in England and Central Europe it persists only for 

 three or four years, a permanent recovery being made. It may 

 be plausibly inferred that the parasite does not find out of the 

 body the conditions neces,sary to its preservation or possibly to its 

 evolution, as they are found on Hungarian and Russian Steppes, 

 and in densely populated China. We have as yet no clear evi- 

 dence of the propagation of the parasite from horse to horse in 

 Central Europe, even in cases where the equine population is 

 dense. 



