666 DIABETES 



within a few hours a severe diabetes ensues. (5) There is no other 

 organ in the body extirpation of which has any similar effect, nor 

 (except for pldorhizinization), is tliere any known means of experi- 

 mentally producing a true diabetes without injury to the pancreas. 

 (6) No toxic substance derived from the bod}^ of diabetic individuals, 

 man or animal, lias been found which is capable of causing diabetes in 

 a second animal. These facts lead to the conclusion {reached hy Min- 

 Jcowski) that pancreatic tissue provides "a something," separate from 

 the pancreatic juice, {internal secretion of the pancreas), the lack of 

 ichich is responsible for the si/mptoms of diabetes. 



Islet Theory: IMorpliologically the pancreas may be regarded as stroma, 

 ducts, acini and islands of Langerhans. It has been proposed, notably by Opie *^ 

 in this country, that the antidiabetic internal secretion of the pancreas is elabo- 

 rated by islet cells. This view finds support in the followinof facts: (1) In 

 diabetes melitus the islets are frequently foimd in a state of hydropic or hyaline 

 degeneration, while tlie remaining organ may appear normal. *o (2) Cancer, pan- 

 creatitis and tiie experimental injection of caustics into the ducts very frequently 

 spare tlie islets and fail to cause diabetes. (3) It is claimed that in ])ancreatic 

 grafts, such as described above, islet cells predominate, while acinus cells and 

 ducts disappear. 



(irafts of this kind consist of much connective tissue, generally more or less 

 infiltrated with round cells, and collections of epithelium. Concerning the latter, 

 remains of ducts and acini are usually present in some proportion, and there axe 

 also epithelial cell masses regarded as islets on morphological groruids. Differ- 

 ences of opinion still exist as to the relative proportion of the diiTerent epitlielial 

 elements. Lombroso,'>o whose exhaustive monograph reviews the literature to 1910, 

 concludes tliat the internal function of the pancreas is not monopolized by islet 

 cells. Bensley si developed intra-vital staining methods which, for tlie first 

 time, made possible the sure differentiation of islet cells from duct or acinus 

 epithelium witliout reference to form or arrangement, and appears to have proved 

 tliat these cells are regenerated from duct epithelivun. lie also showed the great 

 normal variations in size and number of islets in different individuals (guinea 

 pigs). His study explains certain of the discrepancies which occur in tlie litera- 

 ture, es])ecially in tlie estimation of the quantity of islet tissue in pancreatic rests, 

 grafts, etc. Recently Allen 52 has reported that when proper sized fragments of 

 pancreas, in connecticm with the ducts, are left in situ, and the remainder of the 

 gland is removed, the subsequent development of severe diabetes may be coincident 

 with disappearance of islet tissue while acinus cells and ducts are unaffected. 

 This operation, according to Allen, is eminently satisfactory for producing ex- 

 perimental diabetes without infection and without loss of the external secretions. 



The Nature of the Internal Secretion of the Pancreas. — Direct evi- 

 dence on this subject is lacking. Such a secretion has never been 

 isolated. Even the experiments made with tlie feeding of fresh pan- 

 creas and with extracts of the gland have led to no definite advance. 

 R<'ports of iniiirovement following the administration of any sub- 

 stance in dialx'tes are worthless unless accompanied by proof of the 

 constancy of the diet, of th(> amount of work performed, and of other 

 factors wliich are known to influence the course of diabetes. Some 



48 "Diseases of the Pancreas,"' LipjiincoH >!c Co., 1910. 

 40 See llomans, .Tour. MvA. Kes.. 1014 (.30), 49. 

 noErgeb. der Plivsiol., 1910 (10), 1. 

 •'.lAm. Jour, of Anat., 1911 (12), 297. 

 52 Gl.vcosuria and Diabetes, Bostojj, 1913. 



