90 Swale Vincent and F. D. Thompson, 



point obtained by Golgi's method. Dale lias also described lumina 

 within the islet area in the toad. 



Laguesse refuses to admit that the islets are simply exhausted 

 masses of acini, or that they are in their nature secreting tubes modi- 

 fied by inanition, and he urges against either of these theories the 

 abundance of the granules of secretion in the islets, the permanent 

 juxta-splenic islet of the Ophidians, and the fact that islets are found 

 in every functional state of the pancreas. The presence of lumina in 

 the islets of reptiles is a strong indication of their origin from alveoli. 



Laguesse in his numerous contributions on the subject has laid 

 stress on the anatomical details above referred to, and inclines strongly 

 to the view that the islets are portions of the secreting tubules tempo- 

 rarily modified for the purpose of supplying an internal secretion. 



Dale employed a new method for investigation of the subject, 

 using secretin^) to exhaust the gland. He concluded that the islets 

 of Langerhans are not independent structures, but are formed by 

 certain changes in the cells of the secreting tissue. The change from 

 the secreting to the „islet" condition may be accelerated by the admini- 

 stration of secretin and as a result of inanition. 



The authore belonging to the second chief group all believe in 

 the internal secretion theory of the islets, and indeed so convinced 

 are many of them that this is the correct theory, that they refuse to 

 admit the statements of the first group who describe changes in the 

 islet in exhaustion and inanition, and the transition forms from one 

 kind of tissue to the other. The chief upholders of this „separate organ" 

 view of the islets are Diamare-), Remile '^), Massari^) and Helly'*) among 

 comparative anatomists, and Ssobolew"), Opie'), and others among 

 pathologists. 



') Bayliss and Siarliiif,', Jouni. of Physiol. Vol. 28, p. 325, 1902; Vol. 29, 

 p. 174, 1903. 



2) Loc. cit. 



■■') Quali. .lonrn. Micr. Sci. Vol. 48, Part. III. Nov. 1904. 



'j i'tciid. i:. Accad. dei Lincei. Vol. 7, p. 134. Rome 1898. 



'') Arch. f. Miikr. Anat. G7. Bd. S. 124. 1905. 



«) Virch. Aich. V. IGH, p. 91. 1902. 



') Bull. Johns lloi.kins Hospital. V..I. II, \k 205, 19O0; .lomn. Kxp. Med. 

 N. Y. 1901. 



