410 Cytology of the Areas of Langerhans 



The adherents of one of these theories have consistently held that the 

 islets produce a substance which, in one or another way, controls carbo- 

 hydrate metabolism. This view, so carefully considered and so capably 

 studied "f.'0,pie ("J. <): iiscs; a particular significance when looked at in 

 the li^ht of my own. experiments on the chemism of the islets, especially 

 as reJSr8S/tlie: J)*reeJjptaJ)iJjty <?f the substances produced by the two 

 types of cells mentione*d*at)6ve. "What may be called the " sugar function " 

 of the islets broadly suggests the outright physiological independence of 

 the islets, and sharply marks off this view from that of the other party, 

 the adherents of which have long urged the probability that the islets 

 are merely exhausted acini which, as such, have no active function what- 

 soever, but are, so to speak, in a state of rest, or obscuration, and, at the 

 end of the cycle, return to the active state as typical pancreatic acini. 

 These being the two main interpretations of the islets, a demonstration 

 that the cells of the islets have a chemical value of their own (and are 

 not, as a matter of fact, merely exhausted -pancreas cells, but cells which, 

 whatever may have been their former state, have, as islet cells, a positive 

 function) would seem to be indirectly confirmatory of the sugar theory, 

 or confirmatory at least of the broader notion that the islets have an 

 independent physiological activity of their own. Such confirmatory 

 evidence, I believe, will be found in the various chemical tests described 

 below. 



* A few words of history, bearing particularly on these considerations, are 

 necessary here. For a larger historical review the reader is referred to 

 Oppel (13) and to Sauerbeck (19). The latter has an ample review of the 

 pathological as well as of the anatomical literature of the islets. * 



The structures called the Islets of Langerhans were discovered by 

 Langerhans (10), who first called attention to them in 1869. The same 

 year (subsequently to Langerhans' s announcement) the name ' Les Hots 

 de Langerhans' was applied to them by Laguesse. Kiihne and Lea 

 afterwards gave them the name of " intertubular cell clumps." They 

 have been called secondary cell groups (by Harris and Gow), points 

 folliculaires (by Eenaut), and Islands of Langerhans (by American 

 anatomists). 



The history of the islets from the date of their discovery until 1886 

 is chiefly interesting for the controversies it contains, and for the opinions 

 hazarded as to the nature and function of the structures. Langerhans 

 himself believed them to be the end-apparatus of nerve fibers. Eenaut 

 (17) described them in a very general way, and was unfortunate in being 

 misquoted by some earlier writer who, since Kenaut's announcement 

 in 1879, has been extensively followed throughout the whole of the 



