496 DIGESTION. 



During starvation the secretion almost stops, but commences again 

 after partaking of food and reaches its maximum, it is claimed by 

 BERNSTEIN, HEIDENHAIN, and others, within the first three hours. 



PAWLOW and his pupils, especially SCHEPOWALNIKOFF, have shown 

 that the above-mentioned (page 492) enterokinase activates the trypsino- 

 gen into trypsin. These observations were later confirmed by others, 

 by DELEZENNE and FROTJIN, POPIELSKI, CAMUS and GLEY, BAYLISS and 

 STARLING, ZUNZ, and have been further studied. The pure juice con- 

 tains, at least as a rule, only trypsinogen, and no trypsin. By mixing 

 with the intestinal juice, or by contact with the intestinal mucosa, the 

 trypsinogen is converted into trypsin by the kinase. Enterokinase, 

 which itself has no action upon proteins, and therefore is not a pro- 

 teolytic enzyme, is not well known. It is made inactive by heating and 

 is therefore considered by many (including PAWLOW) as an enzyme. 

 Others, on the contrary, like HAMBURGER and HEKMA, DASTRE and 

 STASSANO, deny the enzyme nature of enterokinase because they find 

 that a certain quantity of intestinal juice will activate only a certain 

 quantity of trypsin. Enterokinase has been found in man and all 

 mammals investigated. According to most investigators it is formed 

 in the glands or the cells of the intestinal mucosa, while according to 

 DELEZENNE it comes from PETER'S patches and from the lymph-glands 

 and leucocytes, hence impure fibrin containing leucocytes acts as a kin- 

 ase. These deductions of DELEZENNE are disputed by BAYLISS and 

 STARLING, HEKMA and others. 



If we accept the view that the juice secreted after partaking food 

 is regularly free from trypsin, still under other circumstances the juice 

 may contain trypsin. Thus, according to CAMUS and GLEY, the juice 

 secreted under the influence of secretin (see below) is not always free 

 from trypsin, and ZUNZ found that WITTE'S peptone or pilocarpine 

 causes a secretion of juice which often contained trypsin and was directly 

 active. According to CAMUS and GLEY not only does an exterior activa- 

 tion of the trypsinogen in the juice take place, but also in the interior 

 of the gland. An auto-activation of the juice in certain cases is also 

 accepted by others (SAwrrscH 1 ). 



The activation of the trypsinogen into trypsin may, in life, be brought about 

 as the researches of HERZEN, which have been substantiated by GACHET and 

 PACHON, BELLAMY, MENDEL and RETTGER, have shown not only in the intestine, 

 but also in the gland itself. This activation of the trypsinogen in the gland itself 

 is caused in a still undiscovered manner by a body of unknown nature formed in the 

 spleen, which is congested during digestion. Such a " charging " of the pancreas 



1 Camus and Gley, Journ. de Physiol. et de Pathol, gen., 1907; Zunz, Recherches 

 sur 1'activation de sac pancreatique par les Sels., Bruxelles, 1907; Sawitsch, Zentralbl. 

 f. d. ges. Physiol. u. Path, des Stoffwechsels, 1909. 



