374 



STOMACH AND INTESTINE. 



certain effete constituents of the blood are 

 secreted into the intestine, in a like state of 

 partial oxidation. But, even could we assume 

 the chemical identity of two substances merely 

 from their having the same overpowering smell, 

 we should still be left in uncertainty, as to 

 whether these odorous matters were excreted 

 directly from the blood into the bowel, or were 

 introduced into it indirectly, by means of the 

 secretion and subsequent metamorphosis of 

 the bile. The very large intestinal constituent 

 of the meconium, associated as it is with an 

 almost inodorous character of this excrement, 

 would indicate that, on the whole, Valentin's 

 view of the biliary origin of the faecal odour is 

 the more correct one. At present, however, 

 a satisfactory decision of the question seems 

 impossible. 



But whether the peculiar odour of the faeces 

 be biliary or intestinal, there can be no doubt 

 that it is derived, in the first instance, from 

 the blood. For the smell of the excrement 

 of any particular species always has a close 

 relation to that odour, which is specific to the 

 body of the animal, and which appears, in va- 

 rious degrees of intensity, in all its different 

 excretions. And it is even stated by Wehsarg* 

 to present differences specific to the individual. 



Finally, we need have little scruple in as- 

 serting, that all the physical properties of the 

 faeces are also in a great measure dependent on 

 that alimentary residuum which usually enters 

 so largely into their composition. The quan- 

 tity of fatty matter and of casein usually pre- 

 sent in the excrement of the sucking-child, 

 the deepening (and finally black) colour of the 

 faeces in persons who feed chiefly on vege- 

 tables, the lactic acid found in the evacuations 

 of carnivora, or the oil which may often be de- 

 tected in the stools of persons by whom even 

 small doses of cod-liver oil are being taken 

 medicinally form instances of this kind, 

 which might obviously be multiplied to almost 

 any extent. Nor is the process always li- 

 mited to a mere admixture or decomposition 

 of the food itself. On the contrary, the 

 metamorphoses which most of its ingredients 

 have to undergo, often react on the secretory 

 contents of the canal, so as to modify their 

 appearances by the addition of properties 

 more or less foreign to them. And nothing 

 but that comparatively uniform admixture of 

 the chief alimentary principles of the food, 

 which we shall hereafter find is absolutely 

 necessary to the life of the individual, will 

 account for even the imperfect uniformity 

 traceable in examining the excrements of 

 large numbers of individuals. 



The reaction of the human faeces is gene- 

 rally acid; sometimes neutral or alkaline. The 

 quantity daily evacuated by a healthy male 

 adult may be estimated as amounting, on an 

 average to about five ounces avoirdupois. 



The specific gravity of the faeces is gene- 

 rally greater than that of water, owing to the 

 solids which they contain. But it is far too 

 variable to allow of any average estimate 



* Microscopische und ChemischeUntersuchungen 

 der Fasces gesunder Menschen. Giessen, 1853. 



being made. For it varies, not merely with 

 the bulk and weight of the alimentary resi- 

 due that forms so large a portion of the or- 

 dinary excrement, but also with the degree 

 in which the faecal mass has been condensed 

 by the absorption of its watery constituents. 

 And it would further seem, that the faeces are 

 capable of being partially dried, and rendered 

 much lighter, by a mechanical admixture of 

 intestinal gases with th/eir substance while 

 still within the body. At least it is very 

 common for different portions of the same 

 evacuation to exhibit very different specific 

 gravities: the first portions of the excre- 

 ment, which previously occupied the lower 

 extremity of the rectum, being much lighter 

 than water; while those subsequently extruded, 

 though less solid, are so much heavier, as to 

 sink rapidly in this liquid. 



The mechanical composition of the excre- 

 ment might almost be deduced from what 

 has already been said of its origin. A large 

 quantity of its mass no doubt consists of un- 

 digested food.* This must, however, be sub- 

 divided into two parts, which have a very 

 different import with respect to the digestive 

 function. One of these, which is usually 

 much the larger, includes all those substances 

 that are incapable of being dissolved by the 

 various secretions poured into the intestinal 

 canal. Such are the harder parts of various 

 animal and vegetable tissues : the sarco- 

 lemma of muscular substance, the cells of car- 

 tilage, fragments of bone, the elastic fibres of 

 areolar tissue ; together with the husks, shells, 

 pods, chlorophyll, epidermis, and various 

 dense membranes, cells, vessels, and fibres 

 of the various fruits and seeds used as food. 

 Some of these tissues quite defend the soluble 

 contents they enclose. The other portion 

 consists of substances which, though really 

 capable of solution in the alimentary canal, 

 have escaped this process: whether from 

 having been taken in too large a quantity, 

 from not having sojourned in the tube during 

 a sufficient interval of time, or from having 

 been exposed to secretions which are par- 

 tially devoid of their proper solvent force. 

 Of these three causes of such an admix- 

 ture, the first is the more common, and pro- 

 bably constitutes an invaluable safeguard 

 against the dangerous results which might 

 otherwise follow every act of over-eating. 

 Hence in the state of repletion, whether 

 relative or absolute, large quantities of fat, 

 muscular fibre, albumen, casein, starch cells, 

 fibrous tissue, and other strictly alimentary 

 substances, escape digestion, and are found 

 in the faeces. And conversely, it is highly 

 probable that individuals (as well as animals) 

 may have their digestive powers so raised by 



* The analyses of Wehsarg assign to the dried 

 substance of this constituent an amount which 

 would probably be equivalent to a proportion of 

 about 13 per cent, of the whole excrement. But 

 we may suspect this to be rather too low an esti- 

 mate; and are at any rate justified in doubting 

 whether the alimentary ingredient could be com- 

 pletely isolated, for the purpose of being thus de- 

 termined. 



