!34 



ON THE DIGESTIVE FUNCTION, ETC. 



who died in one of the public hospitals of this metropolis, and who had 

 some years before swallowed a number of clasp-knives out of hardihood, 

 their handles were found digested, and their blades blunted, though he 

 had not been able to discharge them from his body. 



It is in consequence of this wonderful power that the stomach is some- 

 times found in the extraordinary condition of digesting itself ; . and of ex- 

 hibiting, when examined on dissection, various erosions in different parts 

 of it, and especially towards the upper half, into which the gastric juice 

 is supposed to flow most freely. It is the opinion of Mr. John Hunter,* 

 however, whose opinions are always entitled to respect, that such a facV 

 can'never take place except in cases of sudden death, when the stomach 

 is in full health, and the gastric juice, now just poured forth, is surrounded 

 by a dead organ. For he plausibly argues, that the moment the stomach 

 begins to be diseased, it ceases to secrete this fluid, at least in a state of 

 perfect activity ; and that so long as it is itself alive, it is capable by its 

 living principle of counteracting the eflfect of this solvent power. Yet a 

 case has lately been publisiied by Mr. Burns of Glasgow, in which the 

 stomach appears to have been eroded, although the death, instead of being 

 sudden, did not take place till after a long illness and great emaciation of 

 the body. It is possible, however, ihS. even here the stomach did not 

 participate in the disease. That the living principle of the stomach is 

 capable, so long as it continues in the stomach, of resisting the action of 

 the gastric juice, can hardly be questioned. And it is to the superior 

 power of this principle of hfe, that worms and the ova of insec.ts are so 

 often capable of existing in the stomach uninjured, and even of thriving 

 in the midst of so destructible an agency. 



But though the solvent juice of the stomach is the chief agent in the 

 process of digestion, its muscular power contributes always something, 

 and in many animals a considerable proportion, towards the general re- 

 sult ; and hence, the shape and structure of this organ, instead of being 

 uniformly alike, is varied with the most skilful attention to the nature of 

 the mechanism by which it is to operate. 



In its general construction the stomach of different animals may be di- 

 vided into three kinds ; membranous, muscular, and bony. The first is 

 cominon to graminivorous quadrupeds, and to carnivorous animals of 

 most kinds ; to sheep, oxen, horses, dogs, and cats ; eagles, falcons, 

 snakes, frogs, newts, and the greater number of fishes, as well as to man 

 himself. The second is common to graminivorous birds ; and to grani- 

 vorous animals of most kinds : to fowls, ducks, turkeys, geese, and 

 pigeons. The third, to a few apterous insects, a few soft-bodied worms," 

 and a few zoophytes : to the cancer-genus, the cuttle-fish, the sea hedges 

 hog ; tubipores and madrepores. 



Of the membranous stomach we have already taken notice in descri- 

 bing that of man ; and at the bony stomach we took a glance in a late 

 lecture on the teeth and other masticatory organs. It only remains, there- 

 fore, that we make a few remarks on that singular variety of the mem- 

 branous stomach which belongs to ruminant animals, and on the muscu- 

 lar stomach of granivorous and graminivorous birds. 



All animals which runvinate must have more stomachs or ven^rfcles than 

 one ; some have two, some three ; and the sheep and ox not less than 

 four. The food is carried down directly into the first, which lies upon the 



♦ Phil. Trans. 1772, 



