RELATION OF STARCH TO BILE. 



51 



57. The comparison of the amount of 

 carbon in the bile secreted by an herbivorous 

 animal, with the quantity of carbon of its 

 tissues, or of the nitrogenized constituents 

 of its food, which in consequence of the 

 constant transformations may pass into bile, 

 indicates, as we have just seen, a great dif- 

 ference. 



The carbon of the bile secreted amounts, 

 at least, to more than five times the quantity 

 of that which could reach the liver in con- 

 sequence of the change of matter in the 

 body, either from the metamorphosed tissues 

 or from the nitrogenized constituents of the 

 food; and we may regard as well founded 

 the supposition that the non-azotized con- 

 stituents of the food take a decided share in 

 the production of bile in the herbivora; for 

 neither experience nor observation contra- 

 dicts this opinion. 



58. We have given, in the foregoing para- 

 graphs, the analytical proof, that the nitro- 

 genized products of the transformation of 

 bile, namely, taurine and ammonia, may be 

 formed from all the constituents of the urine, 

 with the exception of urea that is, from 

 hippuric acid, uric acid,allantoine; and when 

 we bear in mind that, by the mere s-eparation 

 of oxygen and the elements of water, cho- 

 loidic acid may be formed from starch ; 



From 6 at.starch=:(C 12 H 10 O 10 )=C 78 H 60 O 60 

 Subtract 44 at. oxygen ? __ H 4 O 48 



4 at. water 



Remains choloidic acid . . . =C 72 H 56 O 12 j 



that, finally, choloidic. acid, ammonia, and 

 taurine, if added together, contain the ele- 

 ments of choleic acid ; 



1 at. choloidic acid C n 

 1 at. taurine . . . = C 4 NH 7 O 10 

 1 at. ammonia . . = N H 3 

 1 at. choleic^cld" CTWFO 2a ;_ 

 if all this be considered, every doubt as to 

 the possibility of these changes is removed. 



59. Chemical analysis and the study of 

 the living animal body mutually support 

 each other; and both lead to the conclusion 

 that a certain portion of the carbon of the non- 

 azotized constituents of food (of starch, &,c., 

 the elements of respiration) is secreted by 

 the liver in the form of bile; and further, 

 that the nitrogenized products of the trans- 

 formation of tissues in the herbivora do not, 

 as in the carnivora, reach the kidneys imme- 

 diately or directly, but that, before their ex- 

 pulsion from the body in the form of urine, 

 they take a share in certain other processes, 

 especially in the formation of the bile. 



They are conveyed to the liver with the 

 non-azotized constituents of the food ; they 

 are returned to the circulation in the form 

 of bile, and are not expelled by the kidneys 

 till they have thus served for the production 

 of the most important of the substances em- 

 ployed in respiration. 



60. When the urine is left to itself, the 

 urea which it contains is converted into car- 

 bonate of ammonia; the elements of urea 



are in such proportion, that ly the addition 

 of the elements of water, ail its carbon is 

 converted into carbonic acid, and all its ni- 

 trogen into ammonia. 



1 at. urea C 2 N 2 H 4 O 2 > 

 H 2 O 2 5 



2 at. water 



2 at. carbonic acid C 2 O 4 

 2 at. ammonia. , N 2 H 6 



C 2 N 2 H 6 O 4 



61. Were we able directly to produce 

 taurine and ammonia out of uric acid or al- 

 lantoine, this might perhaps be considered 

 as an additional proof of the share which 

 has been ascribed to these compounds in 

 the production of bile ; it cannot, however, 

 be viewed as any objection to the views 

 above developed on the subject, that, with 

 the means we possess, we have-not yet suc- 

 ceeded in effecting these transformations out 

 of the body. Such an objection loses all its 

 force, when we consider that we cannot 

 admit, as proved, the pre-existence of tau- 

 rine and ammonia in the bile; nay, that it 

 is not even probable that these compounds, 

 which are only known to us as products of 

 the decomposition of the bile, exist ready 

 formed, as ingredients of that fluid. 



By the action of muriatic acid on bile, 

 we, in a manner, force its elements to anite 

 in such forms as are no longer caparle of 

 change under the influence of the same re- 

 agent; and when, instead of the acid, we 

 use potash, we obtain the same elements, 

 although ai ranged in another, and quite a 

 different manner. If taurine were present, 

 ready formed, m bile, we should obtain the 

 same products by the action of acids and of 

 alkalies. This, however, js contrary to ex- 

 perience. 



Thus, even if we could convert allanJoine, 

 or uric acid and urea, into taurine and am 

 monia, out of the body, we should acquire 

 no additional insight into the true theory of 

 the formation of bile, just because the pre- 

 existence of ammonia and taurine in the 

 bile must be doubted, and because we have 

 no reason to believe that urea or allantoine, 

 as such, are employed by the organism in 

 the production of bile. We can prove that 

 their elements serve this purpose, but we 

 are utterly ignorant how these elements 

 enter into these combinations, or what is 

 the chemical character of the nitrogenized 

 compound which unites with the elements 

 of starch to form bile, or rather choleic acid. 



62. Choleic acid may be formed from 

 the elements of starch with those of uric 

 acid and urea, or of allalitoine, or of uric 

 acid, or of alloxan, or of oxalic acid and 

 ammonia, or of hippuric acid. The possi- 

 bility of its being produced from so great a 

 variety of nitrogenized compounds is suffi- 

 cient to show that all the nitrogenized pro- 

 ducts of the metamorphosis of the tissues 

 may be employed in the formation of bile, 



