PANCREAS. 



than in the adult ; a statement that my own 

 frequent observations have verified. 



The specific gravity of this gland, accord- 

 ing to Muschenbroeck*, is, compared to water, 

 as 2029 to 1000. 



General appearance. The best view of 

 the external appearance of the pancreas is 

 obtained on its anterior surface where it can 

 be seen, through the peritoneum covering it, 

 without any disarrangement of its structure. 

 It is seen to be of a pale, clear, flesh colour, 

 in which it strongly contrasts with the white 

 cellular tissue investing it, with the yellow fat 

 with which it is often surrounded, and with 

 the grey and dingy coloured absorbent glands 

 which lie contiguous. On looking more closety, 

 it is seen to be mapped out into lobules, and 

 this mapping out is sometimes more conspi- 

 cuously marked by the septa of areolar tissue 

 that separate the* lobules being loaded with 

 fat. The lobules are of very various shapes 

 and sizes, from an eighth to three quarters of 

 an inch in diameter, closely packed so as to 

 fit into one another, and presenting an even 

 general surface. But on a closer examination 

 we see that these lobules are themselves sub- 

 divided by less conspicuous septa into a great 

 number of smaller lobes ; and these again, 

 especially if assisted by a little separation with 

 a fine knife or needle, are seen to consist of 

 numerous minute granules, or acini, as they 

 are termed, which, as far as the scrutiny of 

 the naked eye goes, appear to constitute the 

 ultimate structure of the gland ; but, as we 

 shall see more fully presently, the microscope 

 shows these in their turn to consist of aggre- 

 gations of follicles, and therefore to be truly 

 compound. Thus a mere inspection of the 

 external surface of the pancreas gives an 

 indication of its internal structure ; we see 

 the acini by their aggregation constituting the 

 lobules, the lobules the lobes, and the lobes 

 the whole organ ; the association by which 

 these parts are bound together being more 

 and more intimate as we descend from the 

 greater to the less ; but all of them, even the 

 smallest, that come under the cognisance of 

 the unassisted vision, being truly composite : 

 this is a common character, and indeed a 



fmeral description, of all conglomerate glands, 

 he pancreas in consistence is moderately 

 firm, the lobules having a considerable degree 

 of hardness, but the whole gland having a 

 certain laxness about it, from the way in which 

 the lobes are hung together by areolar tissue. 



There is no proper capsule to the pancreas : 

 the areolar tissue which invests it does so 

 very unequally in different parts, and is strictly 

 continuous on the one hand with that which 

 attaches it to neighbouring parts, and on the 

 other with that which penetrates between its 

 lobules to the internal parts of the organ. On 

 the anterior surface tjjis areolar tissue is so 

 deficient that the structure of the gland is in 

 no way concealed by it. 



Internal structure. On cutting into the 

 pancreas, we see that it is the same through- 

 out its mass as it is on its surface ; that it is 



* Introdt ad Philosoph. Natur., p. 556. 



solid and homogeneous ; that one part exactly 

 resembles another ; that there is the same 

 aggregation of the acini into lobules and of 

 lobules into lobes, and the same nesting in 

 capsules of areolar tissue by the elasticity of 

 which the acini and lobules are made to pro- 

 trude from the cut surface, whereby it be- 

 comes granulated and nodular ; and this 

 irregularity of surface is almost the only 

 difference between the appearance of a section 

 and that of the external surface as just now 

 described. A good idea of the absolute and 

 relative size of the different elements may be 

 obtained by a section : the lobes may be said 

 to have an average diameter of of an inch ; 

 the lobules J^, or \ of the lobes ; the acini 

 TfL of an inch* ; but all the measurements are 

 liable to the greatest variety. 



The areolar tissue, less abundant than in the 

 salivary glands, consists almost entirely of the 

 white fibrous element, and the areolae are very 

 lax and large : it is most abundant near the 

 centre of the gland around the duct, and 

 about the head of the pancreas, where it forms 

 a firm and intimate union between the gland 

 substance and the duodenum. 



The duct of the pancreas, which has been 

 called the canal of Wirsung, from its dis- 

 covery by that anatomist in the year 1642, 

 passes from left to right throughout the en- 

 tire length of the organ, beginning within a 

 few lines of its splenic extremity, by the 

 union, at an acute angle, of two or more 

 minute ramusculi, and emptying itself into 

 the duodenum at or near the junction of its 

 vertical and inferior-horizontal portions. Its 

 course is somewhat sinuous ; it lies, on 

 the average, about equidistant between the 

 upper and lower margin, but nearer the pos- 

 terior than the anterior surface. It is alto- 

 gether concealed by the gland structure, even 

 its point of entrance into the wall of the 

 intestine. After originating in the manner 

 described, it receives continuously in its 

 course small branches which enter it at right 

 angles, and which, unlike the main duct, are 

 perfectly straight and not sinuous, and mostly 

 single and unbranched, each coming from its 

 own appropriate lobe, without receiving any 

 accessory branches from neighbouring ones ; 

 so that they look, as Cruveilhier has said, like 

 the legs of a centipede, of the which the main 

 duct forms the body. By these tributary 

 ducts the calibre of the main canal is gradu- 

 ally increased till it reaches a diameter, at 

 the right extremity of the gland, of ^th of an 

 inch. It is of an opaque white, and there- 

 fore easily distinguishable from the gland 

 substance. Its walls are thin and elastic, but 

 dense and firm. In the tenuity of its walls it 

 stands in strong contrast with the ducts of 

 the salivary glands ; but, like them, it is con- 

 tinuous, by its external loose fibrous coat, 

 with the areolar tissue of the gland. Just 

 before entering the intestine the duct com- 



* This last measurement is taken from the rabbit, 

 as it is difficult to isolate the acini of the human 

 pancreas, or to take their measurement in situ, 

 without isolation ; but the measurement in the 

 human subject very nearly approaches it. 



