December 25, 1891.J 



SCIENCE. 



357 



PHYSIOLOGY OF GASTRIC DIGESTION. 



The foundations of our knowledge of the physiology of 

 gastric digestion were undoubtedly laid by the careful study 

 of the historical case of gastric fistula by Dr. Beaumont — 

 the case of Alexis St. Martin. Animal experimentation and 

 the test-tube reactions of the laboratory cannot be compared 

 in accuracy to observations made directly upon the I'.ving 

 human organism, when these rare opportunities arise which 

 permit of such a study. Then, too, it may happen that a 

 considerable rectification of current physiological doctrine 

 has to be made, and the laboriously gathered results of many 

 observers have to be replaced by those made upon a single 

 case. Much depends, then, upon the skill and thoroughness 

 with which the study of the processes in the human subject 

 are undertaken. 



It must be admitted that these qualities are conspicuous in 

 the recently published records of a study of the chemical 

 processes of the small intestine by Drs. McFadden, Nencki, 

 and Sieber. The subject of their researches, says Lancet, 

 was a female patient under the care of Professor Kocher, in 

 whom an intestinal tistula had resulted from excision of a 

 portion of gangrenous intestine due to strangulated hernia. 

 The false anus was situated in the ileum just above the ileo- 

 csecal valve, so that the materials escaping thereby were 

 wholly composed of the chyme which had passed through 

 the whole length of the small intestine. For a period of 

 nearly six months the woman lived under these conditions, 

 permitting of a long series of observations relative to the 

 time and character of intestinal digestion under varying 

 forms of diet, etc. At the end of that time Professor Kocher 

 re-established the natural channel by means of an operation 

 which proved perfectly successful. It may be remarked at 

 once that during the whole period when there was practically 

 no large intestine the patient gained in weight, and, as the 

 urinary analysis showed, eliminated a fairly normal quantity 

 of urea. 



The procedure consisted in adapting a flexible tube to the 

 fistulous outlet, so as to collect all the material that escaped, 

 and to note its characters under varying circumstances. In 

 consistency this "chyme" — if it may be so termed — was 

 more fluid and diarrhoeal when the diet was albuminous 

 than when it was mainly of a vegetable nature. It was seen 

 that the flow of chyme from the small into the large intes- 

 tine is steadily continuous, being least marked during the 

 night, owing to no food being then taken ; and by some in- 

 genious experiments (e.g., the addition of hard beans to the 

 food, or of salol, which allowed of the detection of salycylic 

 acid in the matters escaping) it was shown that the passage 

 of foods from mouth to csecum occupies at the least two 

 hours: but all traces of the substances introduced did not 

 disappear for from nine to fourteen or even twenty-three 

 hours. The rate of flow, of course, bears much relation to 

 the consistency of the intestinal contents. As regards the 

 nature and properties of the evacuated materials, it is noticea- 

 ble that they were almost free from odor, containing hardly 

 any products of albuminous disintegration, such as indol and 

 sulphuretted hydrogen; they were slightly acid in reaction, 

 tinged yellow by bilirubin, and, according to the predomi- 

 nance of flesh or starchy matter in the food, showed muscle 

 fibre, albuminous granules, vegetable fibres, starch granules, 

 etc., and invariably a large number of various forms of 

 bacteria. The filtrate yielded albumen, mucin, peptone, dex- 

 trose, the two forms of lactic acid, acetic acid, and the biliary 

 acids and bilirubin. 



The authors enter very fully into the characters of the 



bacteria they find, many forms being special to the small 

 intestine, others existing also in the mouth ; but, passing over 

 these, which would entail a full description to be intelligible, 

 we may glance at the main results of their researches, which 

 somewhat modify accepted physiological teachings. One 

 point of interest is the fact that albumen is hardly, if at all, 

 decomposed in the small intestine. Even the action of the 

 tyrosin of the pancreatic juice is small, for leucin and tyrosin 

 were not to be found. Probably, in health, albuminous dis- 

 integration takes place chiefly in the large intestine, and it 

 is only in disease that it occurs in the stomach or small in- 

 testine. Amongst the products of such decomposition are 

 iodol, skatol, phenol, sulphuretted hydrogen, carbonic acid, 

 methyl mercaptan, etc., all of which may be regained from 

 the large intestine. The bacteria of the small intestine are 

 concerned in the disintegration of the carbo-hydrates into 

 lactic, acetic, and succinic acids, and also intoethylic alcohol. 

 The authors, in noting this last-named fact, cannot avoid a 

 thrust at the total abstainers. It is generally believed that 

 the chyme is rendered alkaline by the' secretien of the small 

 intestine, but they find that, owing probably to the reinforce- 

 ment of gastric acidity by the organic acid resulting from 

 sugar, the total quantity of acid is more than can be neu- 

 tralized by the bile, pancreatic, and intestinal juices. If, 

 however, the alkalinity of these fluids be diminished, the in- 

 tpstinal contents are hyper-acid, and mucin is precipitated 

 instead of being intermingled with the chyme. This ex- 

 plained the diarrhceal quality of the evacuations noted 

 to be associated with a large amount of sugar and organic 

 acid in the chyme. On the other hand, an excess of alka- 

 linity favors putrefactive decomposition, the acids apparently 

 holding in check the bacteria concerned in albuminous disin- 

 tegration. A marked contrast in this respect was exhibited 

 between the small and large intestine. Putrefactive bacteria 

 could hardly be at all isolated from the former, whilst they 

 abounded in the latter; but this is not owing to the influence 

 of bile, which Nencki showed to have no real antiseptic 

 property. 



The part played by bacteria in intestinal digestion is limited 

 probably to the fermentation of sugar and carbo hydrates 

 generally, the excess of acid resulting from this fermentation 

 being neutralized by the alkaline intestinal juice. But, much 

 as bacterial life abounds in the intestinal canals, varying 

 according to the kind and quality of the ingesta, it does not 

 appear that the processes initiated by these organisms are of 

 such value or importance in nutrition as the chemical fer? 

 ments. Certainly the patient who was the subject of these 

 observations gained in flesh, although for six months she 

 was deprived of all the bacterial processes that go on in the 

 large intestine. 



OCEAN CURRENTS AND TEMPERATURES IN EAST 

 ASIATIC WATERS. 



Under this title Dr. Gerhard Schott contributes to a recent 

 number (ix.) of Petermann's Mitteihmgen an interesting paper, 

 which contains new information regarding the course of the Kuro- 

 Shiwo and other currents in Chinese waters, and also as to ocean 

 temperatures. The conclusions arrived at by the author are based 

 upon researches made by him among the archives — principally 

 ships' journals — of the German Admiralty, which contain obser- 

 vations of great value to science. With regard to the Kuro- 

 Shiwo, tlie general result of Dr. Schott's researches, sajs the Pro- 

 ceedings of the Rojal Geographical Society, is that this great 

 ocean current is not bo extensive as hitherto supposed. Through- 

 out the whole of the year the warm stream is confined as a con- 

 stant current exclusively to the weit side of the line of islands. 



