VOMITING. 155 



The frequent raptures of the stomach have been ascribed 

 to active muscular effort of the organ, but I regard them as 

 due to the pressure of the impacted mass on the paralysed 

 coats. I say paralysed coats, because all hollow organs, 

 unduly distended, suffer a kind of paralysis, or are stretched 

 beyond the limit within which they can act. Doubtless 

 when the muscular coat has partially given way, the pres- 

 sure during the efforts to vomit would increase the hernia 

 of the mucous lining, and favour the regurgitation. 



Admitting, therefore, the fact that horses are not liable to 

 vomit, because they are not subject to impressions by emetic 

 substances, yet I find that when they do vomit, the conditions 

 of distention of the stomach, rupture of this organ, or dilata- 

 tion of the oesophagus, one of which is essential to the act, are 

 precisely those which overcome the only mechanical impedi- 

 ment, and which is the disadvantageous position of a narrow 

 cardiac opening with a folding of the internal lining of the 

 organ. 



My brother says, in his last Memoir on the subject:* 

 " Comparing the stomach of a horse and of a dog in the 

 body and on the dissecting table, it is obvious that the 

 mechanism of the latter must, from its shape and mode of 

 construction, be more simple than the former; it is obvious 

 that extrinsic pressure must produce greater results on the 

 thin, simple, tube-like viscus of the flesh-eater, than on the 

 thick, short, and pouched stomach of the great solipede; but 

 the latter, like the former, has provision for movement, and 

 its construction involves no condition which can act as an 

 impediment to any movement which its nervous affinities 

 may stimulate." Admitting this almost without qualifica- 

 tion, it is clear that the cardiac opening is, in the horse, 



* The Veterinarian, 1857. 



