440 CHEMISTR Y OF THE DIGESTIVE PROCESSES, 



after its removal from the body, and proved that the peptone remained 

 unchanged. Also, when a small quantity of peptone or albumose was 

 slowly injected into a mesenteric vein, this was not assimilated, but 

 appeared afterwards in the urine, showing that it had not been altered 

 by the liver. Shore x circulated peptone not only through the liver, but 

 through the spleen also, by injecting into a splenic artery, and arrived at 

 similar results ; practically, all the peptone appeared again in the urine 

 unchanged. 



These results show that the albumose and peptone do not even enter 

 the portal circulation as such ; the only remaining place where they can 

 undergo modification is in the wall of the intestine itself, and the 

 following experiments show that this is the seat of change. 



Ludwig and Salvioli 2 separated a loop of intestine in the dog with 

 the attached portion of mesentery, and rfijected a gramme of albumose and 

 peptone in 10 per cent, solution, ligaturing the piece of intestine at both 

 ends. The piece of isolated intestine was maintained alive by circulating 

 through it warm defibrinated blood diluted with normal saline, by means 

 of a cannula inserted into that branch of the mesenteric artery which 

 had supplied the loop (anastomosing arterial branches being excluded by 

 ligatures), the blood, after circulating, flowing away by the corresponding 

 branch of the mesenteric vein. After four hours of perfusion in this manner, 

 the piece of intestine and the defibrinated blood having been all the time 

 maintained at the body temperature, the remaining contents of the intes- 

 tine and the circulating fluid were examined for albumose. The intestine 

 contained about half a gramme of coagulable proteid, and only traces of 

 albumose, while the defibrinated blood contained no albumose whatever. 

 Therefore the albumose must have disappeared in the intestinal wall. 



Hofmeister 3 investigated the organs of dogs killed during proteid 

 digestion as to their content of albumose, and found it present in the 

 mucosa (only) of the stomach and intestine, as well as in small quantities 

 in the blood, and in four out of ten cases in the spleen ; in the other 

 organs it was entirely absent. He also showed experimentally that this 

 albumose underwent a rapid change. 



A fresh stomach was divided into two symmetrical halves, or a piece of 

 small intestine longitudinally into two similar pieces. 



The surface of the mucous membrane was washed clean with saline, then 

 one of the two pieces in each case was thrown immediately into boiling water, 

 while the other was similarly treated after being first kept for some time in a 

 moist chamber at 40 C. More peptone was always found in the first piece 

 than in the second, and when the second piece had been kept for a sufficient 

 time (1 to 2 hours) at body temperature, previous to placing in boiling water, it 

 was found to contain no albumose whatever. In another experiment, while 

 one piece was thrown, as before, immediately into boiling water, the second was 

 thrown for some minutes into water at 60 C., and then kept as before at 40 

 C. for two hours ; the result now obtained was that both pieces contained an 

 equal amount of albumose. Since most enzymes would not be affected by such 

 a preliminary treatment, while living cells would be destroyed, this indicates 

 that the cells of the mucosa do not owe their activity to contained enzymes. 



1 Journ. Physiol., Cambridge and London, 1890, vol. xi. p. 559 ; Verhandl. d. X. 

 internal, med. Cong., Berlin, 1891, Bd. ii. Abth. 2, S. 31. 



2 Arch.f. Anat. u. Physiol., Leipzig, 1880, Supp. Band, S. 112. 



3 Ztschr. f. physiol. Chem., Strassburg, 1882, Bd. vi. S. 51 ; Arch. f. exper. Path. u. 

 PharmakoL, Leipzig, 1885, Bd. xix. S. 8. 



