THE PANCREAS AS AN EKDOCRIN GLAND 713 



in 1909, discovered that the parabiosis of a depancreatized dog with a 

 normal animal either prevented diabetes 01 reduced the glycosuria to one 

 of 'a slight degree. From this it can be assumed that the normal dog 

 furnishes some substance to the blood which, carried into the depan- 

 creatized dog enabled it to assimilate sugar. 



In 1911, Carlson and Drennan found that glycosuria did not follow 

 total pancreatectomy in a pregnant dog until after the fetus was re- 

 moved. In 1913, Lafon confirmed this important discovery, and ex- 

 plained the prevention of diabetes in the mother before delivery as due 

 to the passage of fetal pancreatic hormones into the maternal circulation 

 supplying her deficiency. It is also possible that her sugar might be con- 

 sumed by the placenta or the fetal tissues. The experiments of Carlson 

 and Drennan, Forschbach and Lafon as such offer strong support to the 

 hormone theory in general but do not bring us any nearer to a knowledge 

 of the nature of the pancreatic function. 



Likewise, the numerous experimental investigations along physiologic, 

 metabolic and biochemic lines have brought us no nearer an explanation 

 of the problem. Some of the more important contributions may be briefly 

 mentioned here. Cohnheim's studies seemed at the time to offer 

 an explanation of the long-sought for internal secretion of the pan- 

 creas. He found that a fresh extract of the pancreas does not de^ 

 stroy sugar, and that muscle juice has only slight action, but when 

 the two are combined the mixture acquired marked glycolytic power. 

 The pancreatic substance is not destroyed by heat, while the muscle fer- 

 ment is. The former is supposed to activate the latter so that the muscle 

 is able to cause the combustion of sugar. These studies were confirmed 

 by numerous other writers, but later writers have thrown doubt on their 

 value. Herter found that if the pancreas be painted directly with a 

 solution of adrenalin a much greater degree of glycosuria is brought on 

 than by subcutaneous intravenous injections of adrenalin. He explained 

 this as due to the greater readiness with which the adrenalin is brought 

 into contact with the pancreas. Loewi found that the introduction of 

 adrenalin into the conjunctival sac of depancreatized dogs or diabetics is 

 followed by a marked dilatation of the pupil. This suggests that the pan- 

 creas secretes a substance antagonistic to adrenalin. This phenomenon is 

 known as the Loewi reaction, and has been confirmed by Biedl and Offer, 

 Falta, Cords and Bittdorf, who obtained positive reactions in a certain 

 proportion of cases of diabetes. Other workers have seen only negative 

 results. Numerous investigators agree in holding the view that the sugar 

 in pancreatic diabetes comes from protein metabolism and from the gly- 

 cogen of the liver as long as this organ contains it, and is passed out of 

 the body through the urine, because neither the muscles can use it nor 

 the liver store it. Vahlen believed that he obtained a substance from the 

 pancreas that produced the destruction of sugar in a purely katalytic 



