PANCREAS OF THE PKi 235 



sr.M.M Ain" 



1. The structural unit is defined as the smallest portion of an 

 organ which is repeated in a similar way throughout, and which 

 contains all the elemental structures of the organ (p. 209). 



2. The pancreas of the adult pig is formed by the repetition, 

 20,000 to 30,000 times, of a structural unit about one millimeter 

 in diameter. The unit is more clearly outlined in the foetus 

 than in the adult. Its size is limited to the area of supply of 

 one arteriole (p. 220). 



3. Pressure of fluid injected into the main duct of the pancreas 

 is equally distributed to all the units. By presumption, the re- 

 verse is true, that is, all the units deliver their secretion against 

 an equal pressure (p. 234). 



4. The pancreatic ducts of the foetus have been injected. 

 Statements of Laguesse and others, that the early pancreatic 

 ducts are plexiform, are confirmed (pp. 221-230). 



5. The main duct of the pig's pancreas and its branches arise 

 by dilatation of capillary ducts in the primitive plexus, in a 

 manner similar to the origin of arteries and veins from capillaries. 

 This observation affords a clear explanation of certain \-ariations 

 in the pancreatic ducts, not understood before (j). 226). 



I wish to express very hearty thanks to Dr. Mall for his kind 

 encouragement and generous provision of materials necessary to 

 this study. 



LITERATURE CITED 



Baldwin, W. M. 1911 The pancreatic ducts in man, together with a study of 



the microscopical structure of the minor duodenal papilla. Anat. Rec, 



vol. 5. 

 Bensley, R. R. 1911 Studies on the pancreas of the guinea-pig. Am. Jour. 



Anat., vol. 12. 

 Cajal, R.\m6n Y, AND S.\LA, C. 1891 Terminacion de los nervos 3' tubos glandu- 



lares de pancreas de los vertebrados. Barcelona. Quoted in Oppel, 



Lehrb. d. Mikr. Anat., Teil 3, p. 776. 

 DoGiEL, A. S. 1893 Zur Frage liber die Ausfiihrungsgiinge des Pankreas dcs 



Menschen. Arch. f. Anat. u. Physiol., Anat. Abt. 

 D'Orville, p. 1745 De fabrica et usu pancreatis: dissertatio phj-.siologica- 



medica. Leyden. 



THE AMKRICA.v .lOI KNAI. OF AN'ATOMY, VOL. Ifi, SO. 2 



