STOMACH AND INTESTINE. 



375 



hunger and need, as to be enabled to extract 

 nutriment from substances that would other- 

 wise defy the action of their gastric and in- 

 testinal juices. In short, these undissolved 

 and insoluble undigested and indigestible 

 constituents of the alimentary residuum may 

 almost be said to merge into each other, ac- 

 cording to the habits of the individual with 

 respect to the ingestion of food. 



That element of the faeces which is derived 

 from the digestive organs of the animal itself, 

 consists chiefly of mucus and precipitated bile. 

 This mucus is, for the most part, structure- 

 less ; but is mixed with variable quantities of 

 scaly epithelium from the rectum in the neigh- 

 bourhood of the anus. In violent diarrhoea, 

 columnar cells from the intestine may also be 

 found in the evacuations : sometimes in the 

 younger cell-form of abortive cytoblasts or 

 nuclei, sometimes in the more advanced state 

 of simple ovoid cells. The latter are sometimes 

 met with in small numbers, even in healthy 

 faeces ; and constitute what are often termed 

 mucus-corpuscles. The biliary constituent is 

 found chiefly in the form of minute amorphous 

 masses or molecules of a resinous character; 

 crystals or plates of cholestearine ; and soluble 

 colouring matter, that often stains the cells 

 just mentioned, as well as the other mechanical 

 constituents of the excrement. 



The crystals of ammoniaco-phosphate of 

 magnesia, which are so often found in the 

 faeces, can hardly be definitely allotted to 

 either of the two foregoing sources. They 

 are easily recognised by their characteristic 

 shape. They were formerly supposed to be 

 peculiar to the stools of diarrhoea and typhus. 

 But they are found in the healthiest fasces. 

 Their occurrence appears to be favoured by 

 all circumstances which further decomposi- 

 tion. They are therefore probably due to the 

 action of ammonia (developed in the faeces 

 before or after their expulsion) upon that 

 neutral phosphate of magnesia, which we shall 

 see forms so large a proportion of the entire 

 saline constituent of the excrement. 



The chemical composition of the faeces will 

 of course exactly correspond with the nature 

 and amount of those substances of which it 

 forms the mechanical admixture. Hence, not 

 only is it impossible to lay down any average 

 that can apply to faeces generally, but it is 

 even probable, that no two specimens of excre- 

 ment are composed of the same proximate 

 constituents mingled in the same proportions. 



Berzelius* analyzed the faeces of a labourer 

 who had fed on coarse, hard-baked bread, with 

 moderate quantities of meat and vegetables. 

 He obtained the following results : 



Water 75'3 



Bile ... -9 

 Substances soluble 



in water 



f Bile . . . -9 \ 



soluble J Albumen . -9 f 



. . . ) Extractive 2 7 ( 



(. Salts . . . 1-2 ) 



jintes- ) 

 in, fat, V 



5-7 



Insoluble residuum of the food 

 Insoluble substances added in the intes- 

 tinal canal : mucus, biliary resin, 

 and sundrv animal matters 



7-0 

 14-0 



102-0 



* Lehrbuch der Chemie. Bd. ix. p. 341. 



"Without, however, impugning the accuracy 

 of an analysis conducted by such an eminent 

 chemist as Berzelius, it seems important to 

 point out that, for physiological purposes, it 

 is all but useless. For not only does it afford 

 no inference as to the quantitative composition 

 of the faeces generally, but it even suggests 

 grave doubts as to the correctness with which 

 its own chief results have been grouped toge- 

 ther. Recalling, for example, our subdivision 

 of the constituents of the faeces into alimen- 

 tary and secretory, we inquire in vain how 

 much of the soluble albumen and extractive 

 of this analysis was derived from the food, 

 and how much may be ascribed to the secre- 

 tions poured into the canal. In like manner 

 we are ignorant whether its fatty constituent 

 was not partly the undigested residue of fat 

 which had been introduced with the food. 

 But from a comparison of this analysis with 

 some observations on the meconium by Hoefle* 

 and Lehmannf, we may conjecture, that while 

 the protein compounds found in healthy ex- 

 crement belong almost exclusively to the food, 

 a small quantity of its elain and margain, and 

 a larger amount of its muco-gelatinous ex- 

 tractive, are derived from the secretions of 

 the animal itself. 



The inorganic constituents of the excre- 

 ment must also vary greatly with the nature 

 and amount of its alimentary residuum. 

 Porter;}; states that healthy faeces, when 

 dried, contain on an average about 6-7 parts 

 per cent, of mineral substances. Wehsarg 

 reckons these salts at 4'1 per cent., from 

 an average of seven analyses. But an analysis 

 by Dr. Percy estimates them at 16*4 per cent. 

 This proportion somewhat approaches that 

 given in the analysis by Berzelius quoted 

 above. It also corresponds with some ana- 

 lyses by Macaire and Marcet || of the faeces 

 of the Dog and Horse, which they found 

 to contain 20 and 25 per cent, of ash respec- 

 tively.^ The soluble salts form between one- 

 fourth and one-third of the whole ash. The 

 phosphates of the earths and alkalies consti- 

 tute about one-third of all the salts present. 

 While the chlorides of the alkalies are reduced 

 to the very small proportion of about one- 

 thirtieth ; a proportion which is about equalled 

 by the whole of the sulphates. The chief re- 

 maining peculiarities worthy of notice are, that 

 the quantity of potash is from 10 to 40 times 

 greater than that of the soda ; and that the 

 magnesia reaches half the amount of the lime. 

 Of these two quantitative disproportions, the 

 first seems due to the food; while the latter has 

 been referred by Berzelius to the more active 



* Chemie und Mikroskop am Krankenbette, p. 85. 



f Op. cit, vol. ii. p. 135. 



i Annalen der Chemie und Pharmacie, bd. Ixxi. 

 p. 109. 



Day's Simon's Chemistry, vol. ii. p. 375. 



I Socie'te' d'Histoire Xaturelle de Geneve, vol. v. 

 p. '230. 



^[ This difference, like that of the nitrogen of the 

 excrement in these animals (4*2 per cent, in the Dog 

 to -8 in the Horse), probably depended on the con- 

 trast between the animal and vegetable nature of 

 their food. 



B B 4 



