Page:Science vol. 5.djvu/21

 jA^UAur 2. 1885.1

��SCIENCE.

��of thertdgc, Ibe neigliboring p^aks rose around tbem: and all New Zealand, from weBtera lo esstem ci>ast, with Ui« ocean beyond on eithersld-;, lay below. Tbe

���story of llie journey U simply and graphically Wid, alid Biigg^ils H writer of mure iiii«lligence and better powtiTsof ohsena(luiillinnlsut secretion, this digestion is accomplished, has 1 the subject of much speculation and of some iriinenta; hut, until recently, neither had doue a Ulaminate the matter. tedaler ' seemed to have gone tartiiwarda solv- Ittie qneslion when he found that a considerable ion of the cellulose of grass looh place in the n of kbeep. lie first enclosed tiro amnll samples V'freah gTMS in cages of germnD-allver wire covered ^^f!tt muslin, and introduced them into the rumen of a liviug aheep. After three days the animal was Killed, the cages removed, and their contents eialn- irieil. It was found that seventy-eight and fuur-tentba pier c«nt of the woody fibre originally present had 1-eendlMOlved. Subseigtieut experiments showed that the fluid obtained from the rumen of a freshly killed sheep had also a powerful solvent action on woody fibre, sad that the mixed saliva had likewise this power. Kxperimenlsun oxen gave nodecislve result: (hose on the horse failecl to show any solvent action o( the saliva upon woody fibre. Hay, and the ' crude fibre ' prepared in the analysis of fodders, were acted upon by the fluid from sheep's rumen, tlKiugb not so enec^tically as was the grass.

These results point unmistakably to (he first slom- .ich of ruminants as one place where cellulose is digested. Hofmeister atcribes to the mixed saliva the power of dissolving it; but some subsequent ei< jierlmeDts by Tappeiner' indicate that thiaiseflected bf a fermentative process, and that the saliva or fluid en used by Hofmeiater served simply iiipply food to the organisms concerned in the t gltdtrmmn'm'-nlralhIaU,.l%t\rg. x.p. M9. iXMa. ehtn. Iirr.. xU 3iM. iti. Zaa anil^V ; XrlUclir. /iir

��fermentation. Tappelner took samples of the eon- teuls of rumen, small intestine, and large Intestine, of a ruminant fed exclasivuly on liay. One sample from each portion of the alimentary canal was ai once boiled: to a second some antiseptic (chloroform, thymol) was added, sufficient to stop the action of organized ferments; while to the third nothing was adde<l.' All were kept warm, aii<l after a time their content of crude fibre was determined- Those por- tions from the ramen and targe Intestine, to which nothing was added, were found to have lost cellulose, while carlicnic acid and marsh-gas were evolved. No loss was observed from the contents of thesmall intes- tines, uor from the samples treated with antiseptics. Further eiperiments showed that this fi-rnienlalion could be produced outside the body. To liay or pure feliuloae, mixed witii extract of meat, and previously heated to 1111° C, a drop of fiuld from the mmen was added. After a few days, active fermentation bf^an. Gas was freely evolved, consisting of about Bei'enly-aix ppr cent of carbonic acid and twenty- four per cent ol marsh-gas, and the cellulose nearly all disappeared. A second kind of fermentation was also observed, wlilch yielded carbonic acid and hydro- gen. In both kinds of fermentation, only the smaller part of the cellnloae was volatilized, most of It being converts into acids of the fatty series.

That cellulose is fermentable is not a new obser- vation; Van Tiegfaem having found that the butyric ferment has the power of decomposing it, with pro- duction of hydrogen, carbonic acid, and butyric acid. Tappeiner's experiments are of interest, because they show that the fermentation takes place also in the alimentary canal. This is shown not only by the disappearance of the cellulose in the experlmenis described above, but also by the presence of the prod- ucts of the fermentation in stomach and intestines. In ruminants the marsh-gas ferraenlalion seems to ])revall. In the stomach of the horse and swine considerable quantities of hydrogen were found. In 1)otb cases acetic acid, aldehyde, and an acid huv- Log the composition of butyric acid, were found.

These results are important in their bearing on our estimates of the nutritive value of fodders. It having been shown that the digestible portion of Ibe crude fibre has the composition of starch, It has generally been assumed to have the same natritire value. Tap- peiner's experlinents show that this is probably not the case. There appears to be a disposition on the ime critics, however, to rush to the opposite and, instead of overestimating the nutritive value of cellulose, to underestimate it. The non- nltrogeuous nutrients are to be regarded as the fuel of the l)ody, and they are of worth to it in proportion to the amount of energy set free by their oxidation to carbonic acid and water. So far as we can see. It h a matter of indifference whether that oxidation begins in the alimentary canal, or not until the sub- stance baa passed Into the circulation. Whatever potential energy is contained in the digested cellulose is yielded up to the body sooner or later, with the exception of that portion which esca]>es in the foi'm of combustible gases, -According to Tappelner, lliis

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