Preliminary remarks on immunity in animal kingdom 61 



a digestive power on any of the alimentary substances, it may act as 

 a ferment of the pancreatic ferments. 



Delezenne, at the Pasteur Institute, has repeated Chdpowahiikoff's 

 experiments. He has confirmed the accuracy of his results and 

 lias added new data of great importance, not only as regards the 

 physiology of digestion but also in relation to the study of immunity. 

 Enterokynase appears from Delezenne's experiments to be a true 

 ferment ; carried down by the same precipitants (collodion, phosphate 

 of lime, alcohol) which enable us to obtain the greater number of the 

 known ferments ; it is sensitive to high temperatures, and even that of 

 65° C. is sufficient to do away with the greater part of its activity. 

 Yet another property of enterokynase, which it possesses in common 

 with the soluble ferments and which has for us a very special interest, 

 is the facility with which it attaches itself to fibrin. By means of flakes 

 of this substance we can at any time remove from a fluid the whole 

 of the enterokynase contained therein. This fixative property is very 

 important in connection with the part which enterokynase plays in 

 digestion. The fibrin to which it has become attached absorbs trypsin 

 with great avidity. If we introduce flakes of fibrin impregnated with 

 enterokynase along with other flakes which have not been in contact 

 with this ferment into a solution of trypsin, the former are digested 

 with great rapidity, whilst the latter do not undergo any change. The 

 fibrin that has fixed enterokynase is capable of clearing a fluid of its 

 trypsin. On the other hand, that which has not been acted upon by 

 the intestinal juice leaves it there almost unaltered. 



It is of the utmost importance that we should inform ourselves as 

 to the origin of the enterokynase of the intestinal fluid. This fluid, 

 when obtained from a fistulous opening, for example, contains mucus 

 and a considerable amount of debris of various kinds of cells. What 

 are the elements which furnish such a remarkable ferment ? Dele- [GG] 

 zenne has obtained a very precise answer to this question. The 

 enterokynase is not contained in the mucus and is not secreted by the 

 intestinal glands ; it comes from the lymphoid organs. 



If the small intestine of a fasting dog be washed carefully with 

 water all the pre-existing enterokynase is removed from it. The 

 Peyer's patches are then removed and treated with chloroform 

 water. The other parts of the small intestine are similarly treated. 

 This fluid dissolves the enterokynase, as it does the other soluble 

 ferments. We find that the Peyer's patches furnish enterokynase, 

 but that the rest of the intestine, including Lieberkuhn's glands, 

 give none. 



