on the (Estrida. 75 



some diseases, and of retarding the progress of others ; of the 

 former, he gives us an example from Linnaeas, " that the gnaw- 

 ings of lice in the head prevent coughs, wheezings, blindness, &c.," 

 and of the latter he instances " the benefit derived from a copious 

 breeding of worms in children of cachectic habits." Mr. Clark 

 appears to include bots in the above class of remedies, and con- 

 siders that they are not only not injurious in themselves, but that, 

 through the stimulus they impart to the stomach in the discharge 

 of its function, they prove really salutary — as the harmless sub- 

 stitutes for actual disease. I have no doubt that where bots are 

 in moderate numbers, and attached to the cuticular coat of the 

 stomach, they interfere little or nothing with the digestive process, 

 or in any way affect the health or vigour of the horse, as, after a 

 certain time, they take their departure, when the self-adjusting 

 vital powers of the organ will speedily restore to a perfectly sound 

 state the parts of it to which these parasites had so long been 

 living appendages. On the other hand, when large quantities of 

 them are found congregated upon the villous coat, especially if 

 located near the distal or pyloric opening of the stomach, which 

 is the most sensible and irritable part of it, and there produce 

 such effects as have been described in a former part of this paper, 

 it becomes impossible to consider them otherwise than injurious, 

 and that they must, under such circumstances, impair materially 

 the health and condition of the animal whose organ of nutrition 

 is thus formidably attacked. Mr. H., an old veterinarian, an in- 

 telligent man and of very extensive experience in the diseases of 

 horses, assures me that in two instances where he had opened the 

 bodies of horses which had died from internal causes, he found 

 the coats of the stomach perforated by bots, so that he could pass 

 the tip of his little finger through the opening, and through which 

 a portion of its contents had escaped into the cavity of the abdo- 

 men. Bots were [)resent in great numbers, and must in tliese 

 cases (if his statement be true) have, most undoubtedly, been the 

 immediate cause of death ; at the same time, it must be remem- 

 bered, that such a fact is not in accordance with the usual pro- 

 cesses of nature during the progress of disease affecting internal 

 organs. 



