378 



STOMACH AND INTESTINE. 



phurettecl hydrogen have never yet been 

 detected in any appreciable quantity in the 

 blood. And hence without assuming their 

 complete absence from this liquid, we may at 

 least infer that they are not present in that 

 amount which would be necessary to explain 

 their secretion from it, to the extent men- 

 tioned in these observations. 



To this we may add, that no parallel to 

 snch a process of gaseous excretion can be 

 observed in the case of any other vascular 

 surface. This statement not only holds good 

 of the serous membranes, but (what is much 

 more conclusive) even of those structures 

 which are specially organized with reference to 

 the giving out from the blood of certain of its 

 gases, and the taking up of others from the 

 surrounding air. It is to the skin and lungs 

 that we should naturally look for evidence of 

 the true secretion of excrementitious or 

 noxious gases from the circulating fluid. And 

 yet, on turning to the results afforded by the 

 eudiometric researches of a number of ob- 

 servers, we find that the gases which we have 

 just stated to be absent from the blood, are 

 equally deficient in the air exhaled from the 

 vessels of these special organs of gaseous 

 excretion. While even the carbonic acid and 

 nitrogen of the intestinal flatus are at once 

 distinguished, by their quantitative relations, 

 from the same gases, as found in the air of 

 expiration. Thus the minute amount of 

 nitrogen in the air exhaled from the lungs is 

 contrasted with an average of 40 per cent, in 

 the gases contained in the intestines; and its 

 proportion to the carbonic acid present, is 

 increased from T ^ n th in the former, to d, or 

 even f ths, in the latter gaseous mixture, 



In conclusion, we may point out, that while 

 the carburetted and sulphuretted hydrogen, as 

 well as the pure hydrogen, of these analyses, 

 can only be explained as the result of a pro- 

 cess which directly or indirectly involves the 

 deoxidation of water, the chemistry of the 

 organism seems always to reverse this process. 

 Far from deoxidating this liquid, there are good 

 grounds for supposing that a quantity of water 

 amounting to nearly ith of the whole aqueous 

 contents of the food is daily formed in the 

 body by a combustion (or in other words, by 

 an oxidation) of the hydrogen of its tissues. 



But some will perhaps think that these con- 

 siderations are sufficiently answered by facts, 

 which deserve more reliance than any such 

 arguments. 



They would possibly instance experiments 

 like those made by Magendie * and Girardin, 

 and confirmed by Frerichsf : in which the de- 

 ligation of an empty portion of intestine had 

 nevertheless been followed by its distention 

 with flatus. Or they might call attention to 

 the tympanites of typhus fever, and other 

 kindred disorders, in which little food has 

 been taken for a long period of time. But a 

 little reflection might teach us that none of 



these instances have absolutely excluded the 

 presence of all alimentary substances ; and 

 that a very small quantity of liquid or solid 

 matter would probably be quite sufficient to 

 yield the gases observed. 



4. Lastly, as regards the intestinal gases 

 present in diseased subjects, we may conjec- 

 ture a fourth source of such elastic fluids : 

 namely, the decomposition of the various 

 secretions of the canal. For it is not too 

 much to assume, that the decomposition to 

 which the alimentary contents of the intestine 

 appear to be often exposed) is sometimes 

 shared by the secretions poured into its* cavity ; 

 especially when we recollect that, in many dis- 

 eases, the state of all the fluids of the organism 

 is frequently such as notoriously favours the 

 access of putrefaction in the tissues after death. 



The gases expelled from the large intestine 

 carry with them the odorous principles of the 

 excrement. It is, indeed, probable that they 

 become impregnated with these volatile sub- 

 stances mechanically, as a necessary result of 

 their contact with them in the bowels. But 

 reasons are not wanting for the conjecture, that 

 the introduction of certain foetid substances 

 into the blood, is subsequently followed by 

 their specific determination to the mucous 

 membrane of the intestinal canal ; which thus 

 forms a channel for their elimination from the 

 system. For after the inhalation of any par- 

 ticularly offensive odour, the fasces and flatus 

 often exhibit what is unmistakeably the same 

 smell, in a very concentrated form. And the 

 active diarrhoea which frequently attends this 

 reproduction of the odour, seems a part of 

 the same effort of nature, towards the removal 

 of what other evidence, beside that of our 

 senses, thus testifies to be an active poison. 



Respecting the laws which regulate the 

 forcible expulsion of these gases from the 

 stomach or intestines, little need here be 

 said. Though greatly influenced by habit, still 

 the act is essentially voluntary. Its mecha- 

 nism is so closely akin to that of defalcation as 

 not to require any separate notice. Whether 

 the immediate stimulus to this expulsive act 

 is always mere intestinal distention, or whether 

 it is sometimes determined by the quality (as 

 well as quantity) of the elastic fluids, cannot 

 at present be decided. 



We are equally ignorant as to how far, fail- 

 ing such an expulsion, these gases are capable 

 of being absorbed into the blood; and if so, 

 where they emerge from the vascular system, 

 or what form they assume in doing so. The 

 small quantity of sulphuretted hydrogen really 

 present in the most offensive flatus, and the 

 comparative harmlessness of carburetted hy- 

 drogen in the proportions in which it would 

 be dissolved by the blood, prohibit us from 

 coming to any conclusion based on the ordi- 

 nary physiological action of these two gases. 

 We can but conjecture, that whatever ab- 

 sorption they may undergo is slow enough 



* The cases of physometra adduced by obstetric 



* Recherches physiologiques sur les gaz intes- authors seem to be examples of a similar decompo- 

 tinaux. 1824. sition occurring in the blood and secretions cou- 



t Op. cit, p. 866. tained in the cavity of the uterus. 



