442 CHEMISTR Y OF THE DIGESTIVE PROCESSES. 



and for the mechanical stimulation its presence gives to the intestinal 

 movements. 



The small amount of vegetable proteid absorbed, compared with that 

 of animal proteid, is in part clue to the envelope of indigestible cellulose 

 by which it is surrounded, in part to the shorter stay in the intestine 

 due to its action in causing increased peristalsis, and in part to its own 

 less digestible character. 



The percentage of various kinds of plant proteid absorbed also varies 

 considerably ; thus the proteids of some leguminous plants and cereals are 

 absorbed nearly as perfectly as those of animal origin, while in most 

 others (potato, lentil) it is much less complete (22 to 48 per cent. less). 

 The percentage of the nitrogen of meat or egg appearing again in 

 the fseces in man, only amounts to 2'5 to 2'8 per cent., that of milk to 

 6 to 12 per cent. 



Considerable tracts of the alimentary canal can be removed or 

 thrown out of action without causing the death of the animal or even 

 causing serious impairment in absorption. 



The stomach was first removed by Czerny l in dogs ; one animal 

 was preserved alive after such an operation for five years ; in the course 

 of two months after the operation it recovered to quite a normal con- 

 dition, and ate, digested, and absorbed all kinds of food. It was finally 

 killed for examination by Ludwig and Ogata, and the dissection 

 showed that only a very small portion of the cardiac end of the stomach 

 remained. 



Ludwig and Ogata 2 further investigated the course of digestion and 

 absorption when gastric digestion is excluded, by another method. They 

 made a fistula beyond the pylorus and inserted into the beginning of the 

 duodenum a small thin rubber ball, attached to a rubber tube, by means 

 of which it could be distended with water under pressure, so as to 

 occlude the intestine from the stomach. In this way gastric juice could 

 be prevented from entering the duodenum, and by feeding from the 

 fistula the effect of intestinal digestion alone be studied. The food was 

 usually completely digested and absorbed, and the faeces presented a 

 normal appearance. Eaw meat was digested much more efficiently than 

 boiled, connective tissue was not so completely digested as in normal 

 dogs, but nevertheless two injections of meat per diem sufficed to keep 

 the animal in equilibrium. 



The stomach has also recently been removed in dogs by F. de Fillipi, 3 

 who found no disturbance in metabolism and no increase in intestinal 

 putrefaction in spite of the absence of hydrochloric acid. 



The same experimenter also removed in a bitch 1/9 metres of the 

 small intestine (almost the entire length), and found no metabolic 

 disturbance, except that the absorption of fat was diminished ; the animal 

 lived, and afterwards brought up a litter of pups in this condition. 

 The author suggests that the large intestine here vicariously took on the 

 absorptive functions of the small intestine. 



Complete or partial extirpation of the pancreas, or ligature of its 

 duct, causes more or less disturbance of proteid digestion and absorption, 

 but not so much as might be expected, in view of the most important 

 proteolytic function of the secretion of this gland. 



1 " Beitrage z. operativen Chirurgie," Stuttgart, 1878, S. 141. 



2 Arch.f. Anat. u. PhysioL, Leipzig, 1883, S. 89. 



3 Deutsche med. Wchnschr., Leipzig, 1894, No. 40, S. 780. 



