SECRETION OF THE DUCTLESS GLANDS. 885 



ical stimulus arising in the cells of the corpus luteum (see section 

 on Reproduction). 



Pancreas. — The importance of the external secretion, the pan- 

 creatic juice, of the pancreas has long been recognized, but it was 

 not until 1889 that von Mering and Minkowski* proved that it fur- 

 nishes also an equally important internal secretion. These observers 

 succeeded in extirpating the entire pancreas without causing the 

 immediate death of the animal, and found that in all cases this 

 operation was followed by the appearance of sugar in the urine in 

 considerable quantities. Further observations of their own and of 

 other experimenters have corroborated this result and added a num- 

 ber of interesting facts to our knowledge of this side of the activity 

 of the pancreas. It has been shown that when the pancreas is com- 

 pletely removed a condition of glycosuria inevitably follows, even 

 if carbohydrate food is excluded from the diet. Moreover, as in 

 the similar pathological condition of glycosuria or diabetes mel- 

 litus in man, there is an increase in the quantity of urine (polyuria) 

 and of urea, and an abnormal thirst and hunger. Acetone also is 

 present in the urine, but not to the same extent as is found in 

 human diabetes. These symptoms in cases of complete extir- 

 pation of the pancreas are followed by en)aciation and nmscular 

 weakness, which finally end in death in two to four weeks. If the 

 pancreas is incompletely removed, the glycosuria may be serious, 

 or slight and transient, or absent altogether, depending upon the 

 amount of pancreatic tissue left. According to the experiments 

 of von Mering and Minkowski on dogs, a residue of one-fourth to 

 one-fifth of the gland is sufficient to prevent the appearance of sugar 

 in the urine, although a smaller fragment may suffice apparently 

 if its physiological condition is favorable. The portion of pancreas 

 left in the body may suffice to prevent glycosuria, partly or com- 

 pletely, even though its connection with the duodenum is entirely 

 interrupted, thus indicating that the suppression of the pancreatic 

 juice is not responsible for the glycosuria. The same fact is shown 

 more conclusively by the following experiments: Glycosuria after 

 complete removal of the pancreas from its normal connections may 

 be prevented partially or completely by grafting a portion of the 

 pancreas elsewhere in the abdominal cavity or even under the skin. 

 So also the ducts of the gland may be completely occluded by liga- 

 ture or by injection of paraffin without causing a condition of per- 

 manent glycosuria. 



On the basis of these and similar results it is believed that the 

 pancreas forms an internal secretion which passes into the blood 



* Minkowski, "Archiv f. exper. Pathologie u. Pharmakologie," 31, 85, 



