3-18 



STOMACH AND INTESTINE. 



those tubes which immediately encircle each 

 follicle. 



When fresh, these tubes always exhibit the 

 structure just described ; their only contents 

 being a clear, structureless, homogeneous fluid. 

 But from their minute size, it is obvious that 

 this fluid can never he obtained from their inte- 

 rior in sufficient quantity for any trustworthy 

 analysis. While unless the secerning process 

 were extremely rapid, even the secretion 

 poured forth into the tube would often be 

 mixed with those coarsely filtered contents 

 of the intestine which can enter its upper orifice 

 from the general cavity of the alimentary canal. 



And as regards all fluids found in the gene- 

 ral cavity of the intestine, we ought never to 

 forget that to procure them in a state of abso- 

 lute purity is impossible. Under normal cir- 

 cumstances, the fluid present in any part of the 

 bowel can only be regarded as a complex mix- 

 ture of several ingredients, all of which are 

 probably themselves undergoing a continual 

 metamorphosis. Could we deduct from the 

 contents of the intestine all chyme, bile, and 

 pancreatic secretion, the residue would be 

 strictly an intestinal juice. And by far the 

 larger quantity of such a juice would be com- 

 posed of the secretion of the intestinal tubes. 

 Now we shall hereafter find that analogy sup- 

 plies us with some plausible conjectures re- 

 specting the fluid secreted by the duodenal 

 glands. ' While the closed follicles which 

 abut on the cavity of the bowel can scarcely 

 furnish sufficient fluid seriously to affect 

 the composition of any mixture which it may 

 contain. Hence whatever the share taken 

 by the villi, the secretory office of these tubes 

 might apparently be to some extent determined 

 from an examination into the chemical and 

 physiological properties of even such an im- 

 pure or mixed intestinal juice. 



The reader will, however, hardly be sur- 

 prised when he is informed, that these condi- 

 tions have never yet been fulfilled; and hence, 

 that a satisfactory account of this interesting 

 fluid remains at present impossible. But he 

 must not therefore think the above allusions 

 superfluous. For it is only by a reference to 

 these conditions of experiment, that we can 

 judge how far we ought to accept the state- 

 ments made by various recent observers re- 

 specting this fluid. 



Thus Frerichs * obtained intestinal juice 

 from fasting cats and clogs, in whom a few 

 inches of intestine had been emptied, and tied 

 at both ends, about five hours before they 

 were killed. Lehmann-j- procured it from a 

 fistula of the small intestine, which had fol- 

 lowed an operation for hernia in the human 

 subject ; and in which another fistula, higher 

 up, gave passage to the ordinary mixed con- 

 tents of this part of the alimentary canal. 

 Zander J instituted fistulae in animals. And, 

 finally, Bidder and Schmidt, who adopted 

 Frerichs' method without obtaining one drop 



* Op. cit. p. 850. 



f Op. cit. vol. ii. p. 112. 



j Koelliker, Op. cit. 



Lehniann, Loc. cit. and Bd. iii. s. 335. 



of intestinal juice, carefully compared the mix- 

 ture withdrawn from simple fistulae, with a 

 very small quantity of a purer fluid which was 

 yielded by dogs in whom the pancreatic and 

 biliary ducts had been tied, and the gall bladder 

 made to discharge its contents externally. 



According to all these observers, the 

 intestinal juice is a transparent, viscid, and 

 strongly alkaline fluid. It contains nuclei, 

 and round or columnar nucleated cells; 

 an abortive cell-growth, the admixture of 

 which does not substantially affect the struc- 

 tureless character of the secretion. Of its 

 composition and reactions we can only say, 

 that it appears to contain mucus and the 

 ordinary salts; which together form a solid 

 residuum, that amounts to about 2 per cent, 

 of the whole quantity of fluid.* 



As regards the physiological properties of 

 the intestinal juice, it has the power of con- 

 verting starch into grape sugar. But however 

 obvious the usefulness of this capacity, it is 

 possessed in an equal degree by so many other 

 animal substances, that it can hardly be re- 

 garded as the specific purpose or function of 

 this secretion.-]- 



But the recent observations of Zander, 

 together with those of Bidder and Schmidt, 

 claim for this secretion a much more impor- 

 tant office : an office which would entitle 

 the whole of the small intestine to that ap- 

 pellation of a " ventriculus succenturiatus, " 

 which was formerly bestowed on the duode- 

 num. These observers agree in the state- 

 ment, that the intestinal juice dissolves protein- 

 compounds, both in and out of the body. 

 And from the careful quantitative researches 

 of Bidder and Schmidt, it would follow, not 

 only that its solvent powers upon these sub- 

 stances are from three to four times greater 

 than those of the gastric juice itself, but that 

 in the Dog, about half the daily albumen of a 

 flesh diet is habitually left untouched by the 

 stomach, to undergo solution in the intestine 

 by the secretion. 



Against such a conclusion I would suggest 

 the following arguments, which together in- 

 duce me to think that this doctrine ought not 

 at present to be accepted. That a large organ 

 like the stomach, with a definite and com- 

 plicated structure, should so incompletely 

 discharge its single chemical function, is a 

 paradox which alone involves a great improba- 

 bility. This suspicion becomes still stronger 

 when we consider that, under normal circum- 

 stances, gastric juice is always conveyed from 

 the stomach into the intestine during the pro- 

 cess of gastric digestion ; while it is evident 

 that none of the experiments by these observers 

 quite exclude the possibility of such a transit. 

 Nay more, if we suppose what is surely not 



* Bidder and Schmidt observed a much larger 

 quantity in the mixed fluid; but point out that the 

 lixed contents would be raised by the addition of 

 the more concentrated secretions of the liver and 

 pancreas. Hence I prefer quoting the estimate 

 deduced by Lehmaun from what was probably a 

 purer fluid. 



f Compare the remarks on the pancreatic fluid, 

 in a subsequent part of this article. 



