cipitate mucin, and the precipitate is soluble in excess. Copper sulphate and ferric chloride, mercuric chloride, lead acetate, potassium dichromate, and potassium alum, all give slimy, gelatinous precipitates. Potassio-mercuric iodide gives no precipitate. Saturation with magnesium sulphate or sodium chloride precipitates mucin; Millon's, Adamkiewicz's, and the xanthoproteic reactions are all given by mucin. By heating with dilute mineral acids, a reducing substance is obtained. Potassium ferrocyanide gives no precipitate, or only a cloudiness in a solution of mucin in dilute hydrochloric acid. A sodium chloride solution can be pretty strongly acidified by acetic acid before precipitation occurs; and potassium ferrocyanide added to such a mixture produces no precipitate. Tannic acid in small quantities causes the liquid to become slimy and thick, and in excess causes precipitation. Of the varieties of mucin hitherto described, this approaches nearest to tendon mucin, but it differs from that in its solubility in dilute hydrochloric acid, and its behaviour to weak alkalis.

W. D. H.

The Mucin of Bile. By L. PAIJKULL (Zeit. physiol. Chem., 12, 196-210).-Landwehr (Zeit. physiol. Chem., 8, 114) was the first to point out that the slimy substance in bile is not true mucin; he considered it to be a mixture of globulin with bile salts. An examination of his analytical results shows that there is some difficulty in accepting this view; for instance, the percentage of nitrogen in bile-mucin is 138; in paraglobulin, 15.85; and in glycocholic acid 2.5; there must therefore be 154 per cent. of glycocholic acid in the mixture called bile-mucin. The percentage of carbon on this calculation ought to be 55 01, but it is only 53:09. Moreover, although Landwehr states that a mixture of sodium glycocholate with serum-globulin has the physical characters of bilemucin, it was found in this research that a mixture of globulin with bile deprived of its so-called mucin did not produce the characteristic sliminess of normal bile. The usual method of preparing mucin is not applicable to bile, as the bile-mucin is slightly soluble in excess of acetic acid. By dialysis, the mucin can be readily freed from bile salts, but not so readily from bile pigment; moreover, putrefaction is apt to ensue when dialysis is prolonged. The method ultimately adopted was to precipitate the mucin with five times its volume of absolute alcohol; the precipitate was collected and freed from alcohol by centrifugalising, redissolved in water, and again precipitated by alcohol. By thus quickly removing the alcohol, the mucin was not rendered insoluble. The properties of a 0.23 per cent. solution of this so-called mucin were as follows:

On heating a neutral solution, it coagulated on boiling. After the addition of a trace of acetic acid, which caused no precipitation at the ordinary temperature, it coagulated on heating, like a proteïd solution. More acetic acid caused precipitation without heat, and the precipitate dissolved in excess although with some difficulty; this acetic acid solution was precipitated by potassium ferrocyanide, potassio-mercuric iodide, mercuric chloride, and tannic acid. Hydrochloric acid in very small quantities caused a flocculent precipitate,

which dissolved easily in excess. Copper sulphate, ferric chloride, potassio-mercuric iodide, lead acetate, and potash alum gave abundant precipitates when added to a neutral solution. Saturation with sodium chloride or magnesium sulphate gave precipitates; the solu tion also gave the xanthoproteic, Millon's, and Adamkiewicz's reaction. A solution of the mucin in hydrochloric acid (0.3 per cent.) gave no precipitate when digested for some time at 40°; but if pepsin were first added, a flocculent precipitate formed, as in solutions of nucleoalbumins. Prolonged heating with dilute mineral acids yielded no reducing substance.

The following are the results of elementary analysis:-C, 50·89; H, 6·735; N, 16·14; and S, 1.66 per cent.

The so-called mucin of bile is regarded, not as true mucin, nor as a mixture of globulin with bile salts, but as a nucleo-albumin. Small quantities of true mucin derived from the walls of the gall-bladder appear to be also present in certain cases. W. D. H.

Physiological Chemistry.

Relation of Carbohydrates in Food to Digestive Ferments. By A. STUTZER and A. ISBERT (Zeit. physiol. Chem., 12, 72—94).— The question of the artificial digestion of carbohydrates is taken up from the same point of view as that of proteïds (Abstr., 1887, 361, 388, 1229); namely, can quantitative estimations be obtained of the digestible and indigestible portions of carbohydrates by the successive treatment of the fodder with the various diastatic ferments? It is already well known that certain carbohydrates, such as starch and sugar, are more digestible than certain others, such as cellulose, which is not attacked by the digestive juices, but only by putrefactive agents.

Standard solutions of ptyalin (from pig's salivary glands) of malt diastase, of pepsin, and of pancreatin were prepared; the two last being the same as those used in previous experiments. Ptyalin acts best at 40°, diastase at 60°; pancreatic fluid acts on starch better in a neutral than an alkaline fluid: not at all in an acid one. Cloverhay, wheat-meal, and white bread were the kinds of food used; and tables are given of the proteïd, fat, carbohydrate, ash, and water in each of these. Fat was in all cases first removed by extracting with ether. 2 grams of the food was used in each experiment; this was boiled with 100 c.c. of water, and when cool the ferment solution was added; 200 c.c. of the ptyalin solution with which it was kept at 37-40° for two hours: or 25 c.c. of the solution of diastase for the same length of time at 60-65°. The residue was then filtered off through asbestos, and exposed to the action of 400 c.c. of the peptic fluid; it was again freed from digestive fluids by filtration before being exposed for three hours to the action of the pancreatic

ferment at 37-40°. The weight of the final residue (minus ash, the carbonic anhydride being driven off by nitric acid) gave the undigested organic substance (a); the nitrogen in this was estimated, multiplied by 6.25, and the product gives the undigested proteïd (b); the difference between (a) and (b) gives the undigested carbohydrate. The first series of analyses are those in which the food was subjected either to the action of ptyalin or diastase, and to the subsequent action in most cases of pepsin. Full details in tabular form are given of these and the following analyses; and the following conclusions are drawn :

(1.) A feebly alkaline solution of ptyalin acts better than a neutral, and this better again than a feebly acid one.

(2.) For substances which are rich in digestible carbohydrates, like wheat-meal, the optimum of digestion with a neutral ptyalin solution (which was the one usually employed) was obtained when 100 c.c. of the solution was present to every gram of the food. When food, such as hay, in which the digestible carbohydrates was small in quantity was used, half this amount sufficed.

(3.) 25 c.c. of the diastase solution was sufficient.

(4.) Ptyalin alone worked better than diastase, but when followed by the action of pepsin they gave identical results.

(5.) Neutral ptyalin solution dissolves some amount of proteïd.

The second series of analyses was one in which the pancreatic fluid alone acted. 100 c.c. of the neutral fluid gave the optimum of digestion on the carbohydrates, but the action was not so great as with ptyalin or diastase alone. Alkaline pancreatic fluid acts best on proteïds.

The third series were experiments in which the action of ptyalin or diastase was followed by that of the neutral pancreatic fluid: the best results being obtained when ptyalin was first used. The additional action of the pancreas is, however, very small.

The fourth series were experiments in which the action of either ptyalin or diastase was followed by that of both pepsin and pancreatic ferment; but the optimum was the same whether ptyalin or diastase was used. Although the pancreatic juice by itself acts on amyloïds best when neutral, yet, after the action of the other ferments, the best results are obtained when it is feebly alkaline.

It is not, however, believed that these results are comparable with what is obtained in natural digestion, because the bacteria which occur in the intestines and which act so energetically on carbohydrates, are left out of account. It is possible, however, that the method of artificial digestion may furnish us with a means of estimating cellulose quantitatively. W. D. H.

Changes in Carbohydrates in the Alimentary Canal. By J. SEEGEN (Pflüger's Archiv, 40, 38-48).-Cane-sugar and starch are the carbohydrates most used as food; the former is inverted in the stomach (Hoppe-Seyler); the latter is converted into erythrodextrin in the stomach, and sugar is formed from it in the intestine by the action of the pancreatic and, according to some, of the intestinal jnice also. Nasse named the sugar so formed ptyalose; v. Mering and

Musculus showed that this is identical with maltose. On the other hand, the sugar present in the blood and that which leaves the liver is dextrose.

The present research is devoted to a reinvestigation of these points. Animals were fed for some days on cane-sugar, and then killed; the contents of stomach and intestines were examined, and the following conclusions drawn: the stomach inverts sugar; besides cane-sugar, a certain quantity of reducing sugar was also found. The small intestine contained no cane-sugar; after boiling the contents with hydrochloric acid, the amount of sugar remained the same; the sugar present is therefore invert sugar; 24 hours after death, no sugar is found in the stomach, and only traces in the intestine, the sugar having been changed into lactic acid. In the portal blood, a certain quantity of reducing sugar is found, but after boiling with acid there was no increase in reduction, showing that cane-sugar is not absorbed as such, or if it is, in such small quantities as not to be recognisable by this method; the latter is probably the more correct statement, as cane-sugar is sometimes found in the urine.

In experiments in which starch (starch-meal, potatoes, and rice) was used, it was found that erythrodextrin was present in the stomach, but only traces of sugar which might have been formed by the saliva, The small intestine also contains dextrin, probably achroodextrin, and a reducing sugar; on boiling the contents of the small intestine with acid, the reducing power is increased; this is due to the conversion of dextrin into sugar; if the dextrin is first precipitated by alcohol, and the residue treated with acid, there is no increase in the reducing power; the sugar is therefore grape-sugar. It is possible that starch is converted into maltose by the pancreatic secretion, and then by the further action of the intestinal juice into dextrose (Brown and Heron, Abstr., 1880, 903). Absorption takes place so rapidly that only small amounts of the products of digestion are obtainable. In the portal blood, dextrose was found, and in one instance dextrin also. W. D. H.

From what Material does the Liver form Sugar? By J. SEEGEN (Pflüger's Archiv, 40, 48-64).-The liver continues to form sugar after removal from the body; in fact, as long as its cells retain vitality and the quantity formed is not in proportion to the glycogen lost (Seegen and Kratschmer, Abstr., 1882, 540). By researches of three kinds, (1) using various materials, for instance, peptones as food; (2) injecting these substances into the blood; and (3) placing the excised liver in contact with them, it was shown that peptone was one substance from which the liver forms sugar. The blood in the hepatic vein contains twice as much sugar as the portal vein, whether the food contains carbohydrate or not; fat and proteïd seem to be the substances from which the liver normally forms sugar. The sugar formed from glycogen by diastatic ferments is maltose, whereas that found in the blood leaving the liver is dextrose.

Chittenden and Lambert (Studies from Lab. Physiol. Chem., Yale Univ., 1885) obtained results which showed that although the total carbohydrates are increased by peptone, the sugar is increased but

little; they adhere to the view generally held that the sugar is formed from glycogen. They also speak of the sugar which leaves the liver as a mixture of maltose and dextrose. A large amount of the present paper is devoted to a criticism of the methods and results of Chittenden and Lambert. W. D. H.

Fate of Lecithin in the Body. By K. HASEBROEK (Zeit. physiol. Chem., 12, 148-162).—Bokay (Zeit. physiol. Chem., 1, 157) showed that the pancreatic juice splits lecithin into a fatty (oleic, palmitic, or stearic) acid, choline or neurine, and glycero-phosphoric acid. The question which is investigated in the present research was what happens to these three products of decomposition. The fatty acid doubtless behaves like fatty acids from adipose tissue, being partly saponified and separated from the body as calcium compounds, partly absorbed and further oxidised in the body to form carbonic anhydride and water. Choline, as has been shown by Brieger's work on ptomaïnes, is a type of poisonous alkaloids obtained by the putrefaction of organic substances. It is perhaps here also obtained from lecithin, which has a wide distribution in the animal kingdom. Putrefaction has an important part to play in the alimentary canal. The process of putrefaction in both neurine and glycero-phosphoric acid outside the body was studied according to Hoppe-Seyler's method and with the apparatus used by him (Zeit. physiol. Chem., 1, 561). A mixture of choline hydrochloride, sewer-mud, calcium carbonate and water was kept at the ordinary temperature, and the gases which came off in large quantities were collected and analysed. They were found to consist of carbonic anhydride 18 to 20, and methane 80 to 82 per cent. After two months, when all evolution of gas had ceased, the liquid residue was examined microscopically, zooglœa colonies being found. Some was injected hypodermically in a rabbit but without ill results. On analysis it was found to contain large quantities of ammonia, and traces of first substitution products; of higher substitution basic products such as trimethylamine there was none. If a similar decomposition occurs in the intestine, it may be concluded that carbonic anhydride, methane, and ammonia are formed from choline there. This gives us a fresh source of methane in the intestine; Hoppe-Seyler and Tappenier (Abstr., 1887, 1131) have shown that cellulose is one source; and Hoppe-Seyler (Abstr., 1887, 1135) has shown that acetates form another. Choline, moreover, is not an unimportant source of marsh-gas, as lecithin is largely contained in eggs, meat, and in leguminous and other seeds.

On subjecting glycero-phosphoric acid to similar treatment, it was not found to yield any gases, or only minute quantities such as probably came from the mud used. The conclusion is therefore drawn that the acid is absorbed as such. This coincides with the observation of Sotnischewsky (Zeit. physiol. Chem., 4, 215), who found it unaltered in the urine. W. D. H.

Relative Nutritive Value of Fat and Carbohydrate. By 0. KELLNER (Zeit. physiol. Chem., 12, 113-115).-By feeding a horse on starch and linseed oil respectively, and calculating the work done, it