INFLAMMATION OF THE BOWELS. 357 



which is represented in the engraving during the course of the 

 first two months of its life, and then it fulfils its allotted career, 

 by letting go and being carried out with the dung. On reaching 

 the outer air it soon assumes the chrysalis condition, and in three 

 or four weeks bursts its covering to become the perfect insect. 



From this history it will be evident that no preventive 

 measures will keep off the attacks of the fly when the horse is at 

 grass, and, indeed, in those districts where they abound, they will 

 deposit their ova in the hair of the stabled horse if he is allowed 

 to stand still for a few minutes. The eggs are, however, easily 

 recognised in any horse but a chestnut, to which color they closely 

 assimilate, and as they are never deposited in large numbers on 

 the stabled horse they may readily be removed by the groom. 

 Unlike other parasites, they seem to do little or no harm, on 

 account of the insensible nature of the part of the stomach to 

 which they are attached, and, moreover, their presence is seldom 

 discovered until the season of their migration, when interference 

 is uncalled for. On all accounts, therefore, it is unnecessary to 

 enter into the question, whether it is possible to expel them; and 

 even if by chance one comes away prematurely it will be wise to 

 avoid interfering by attempting to cause the expulsion of those left 

 behind. 



INFLAMMATION OF THE BOWELS. 

 (Peritonitis and Enteritis.') 



A reference to the cut of the abdomen and its contents, oppo- 

 site page 278, will explain that there are two divisions of the 

 abdominal serous sac, one of which lines the walls of the cavity, 

 and the other covers the viscera which lie in it. In human medi- 

 cine, when the former is inflamed, the disease is termed peritonitis , 

 and when the latter is the subject of inflammatory action it is 

 called enteritis. But though in theory this distinction is made, in 

 practice it is found that the one seldom exists without the other 

 being developed to a greater or less extent. Veterinary writers 

 have generally taken the nomenclature adopted in human ana. 

 tomy and pathology, but in regard to the inflammations of the 

 bowels they define peritonitis as inflammation of the peritoneal or 

 serous coat, and enteritis as inflammation of the muscular coat. 

 My own belief is, that during life it is impossible by any known 

 symptoms to distinguish the exact locale of any inflammation of 

 the bowels but that of their mucous lining, which will presently 

 be described, and that wherever the actual serous covering of the 

 bowels is involved the muscular fibres beneath it will be implicated, 

 but that the serious and fatal symptoms manifested in such cases 

 are not dependent upon the latter, but are due entirely to the 

 lesions of the serous coat. I have examined numberless fatal 



