DIGESTION. 105 



markedly distinct and dare not be confounded. Eennin seems to re- 

 quire the presence of calcium salts before it can produce coagula- 

 tion, which, when it does occur, presents the casein in the form of a 

 coherent clot entangling in it the fats present. There is squeezed out, 

 as it were, from the closely formed curd a clear, yellowish liquid, 

 known as the whey, containing some proteids with the salts and sugar 

 of the milk. 



On the other hand, experimentation shows that the ferment in 

 pancreatic juice does not require the presence of the calcium salts for 

 precipitation of caseinogen; further, that the precipitate which does 

 occur is very -finely granular in nature; at the same time the milk 

 seems to undergo no change in its fluidity, as far as can be dis- 

 tinguished by the naked eye. The presence of certain salts, which 

 entirely check the action of rennin, but slightly hinder the action of 

 the pancreatic ferment. It is believed that this pancreatic casein is 

 not a true casein, for rennin placed in its presence has the power to 

 change it still further, the resultant product being identical with 

 true casein. 



Effects Resulting Upon Removal of Pancreas. 



It was in 1889 that von Mering and Minkowski by experiment 

 upon the lower animals proved that removal of the pancreas was in 

 every case followed by the appearance of dextrose in the urine, a con- 

 dition known as diabetes, plus those symptoms marking the absence 

 of pancreatic secretion in the intestinal canal during digestion. In 

 the blood there was as much as 0.5 per cent., while in the urine the 

 8-per-cent. mark was reached. These investigators found that animals 

 presented the identical characteristics as do human beings suffering 

 from the same disease, namely : an abnormal excretion of water with 

 the appearance in the urine of dextrose, acetone, and aceto-acetic acid. 

 Another step was determining that this condition is not due to want 

 of the pancreatic secretion in the intestine by tying the duct of Wir- 

 sung or else plugging it and its branches with paraffin, but allowing 

 the organ to remain in its proper position in the body. The pres- 

 ence of a certain proportion of the whole gland, even though its secre- 

 tion be not allowed to reach the intestines, will prevent diabetes; 

 absence of this diseased condition is still maintained though a portion 

 of the gland be removed from its normal position to be transplanted 

 elsewhere. 



From these data it would seem that the pancreas possesses virtues 

 in the general economy other than merely producing pancreatic juice. 



