82 THE MODERN HORSE DOCTOR. 



insensible perspiration ; such an atmosphere is no less injurious 

 than that of a crowded, unventilated stable. A horse may be 

 attacked with pneumonia, which may run through its various 

 stages, and finally end in tubercles, or pulmonary consumption. 

 Perverted nutrition, in a constitution predisposed to the develop- 

 ment of this malady, may be equally prolific with the former; 

 for if the fibrine of the blood be imperfectly elaborated, it is less 

 fit to undergo organization ; and, consequently, instead of being 

 converted into living tissue, part of it is deposited as an unorgan- 

 ized mass, resulting in tubercle. In the predisposed, such de- 

 posits take place more frequently in the lungs than any other 

 part, and besides impeding the circulation and respiration, they 

 produce irritation and inflammation, in the same manner that 

 other foreign bodies would when imbedded in any of the tissues ; 

 so that the issue, although often postponed for several years, is most 

 generally fatal. Most medical writers agree in the opinion that, 

 when tuberculous matter is once deposited in the lungs, there is 

 no getting rid of it. Microscopic examinations of tubercular 

 matter show that it consists of half-formed cells, fibres, &c, 

 together with a granular substance, which seems to be little else 

 than coagulated albumen. 



As regards the existence of tubercles at birth, Mr. Percivall 



loaded with dampness, is breathed, there is rather an absorption than an exha- 

 lation of aqueous vapor ; and the same may, probably, take place, in a less de- 

 gree, in an ordinary atmosphere, when the body has been drained of its fluid. 

 In this manner, perhaps, we are partly to account for tbe extraordinary in- 

 crease in weight which the body undergoes by absorption from the atmosphere, 

 under peculiar circumstances. 



" That absorption may take place through the lungs is evident also, from 

 the effects upon the system of certain gases, which act as virulent poisons, 

 even when respired in small proportion. Thus a bird is speedily killed by 

 breathing air which contains no more than l-1500th part of sulphuretted hy- 

 drogen ; and a dog will not live long in an atmosphere containing 1-S00th part 

 of this gas. 



" The effects of carburetted hydrogen are similar ; but a larger proportion is 

 required to destroy life. Both these gases are given off by decomposing ani- 

 mal and vegetable matter, the neighborhood of which is very injurious to 

 health. It is chiefly by preventing the accumulation of such substances that 

 an efficient drainage becomes so important a means of preserving health and 

 promoting life." — Dr. Carpenter on Secretion, 



