148 TURNER, OX TRANSPARENT INJECTIONS. 



other. The injecting fluid which I used -was of the same 

 composition as that recommended by Dr. Lionel Beale, and 

 employed by him with such success in his investigations into 

 the minute structure of the liver. It is composed of a mix- 

 ture of glycerine, spirits of wine, and water, in which Prussian 

 blue, obtained by precipitation, is suspended. 



This injection possesses the great advantage of flowing 

 easily when cold along the ducts, and, from its great trans- 

 parency, the organ into which it is thrown can be examined 

 by transmitted light, and by high magnifying powers, so that 

 the connections and relations of its component structures can 

 be much more readily traced than in those cases where 

 opaque injections are employed. It is hardly possible, how- 

 ever, to make a complete injection of all the ultimate lobules 

 throughout the pancreas ; for in many parts they appear to be 

 so filled with secreting cells, and the fine ducts proceeding 

 from them are, in a similar manner, so blocked up with 

 closely packed epithelium, that the injection cannot flow 

 along them. But this does not throw any obstruction in the 

 way of an examination of those lobules into which the injec- 

 tion has passed ; it rather tends to facilitate it, for the outline 

 of the ultimate follicles, distended by the blue .fluid, comes 

 out more distinctly, by the contrast which it presents to the 

 paler non-injected portions. 



It will be frequently found advantageous to examine those 

 lobules, the sacculated follicles of which are only partially 

 filled by the injection; for in them the general and relative 

 arrangement can be more distinctly seen than in those lobules 

 which are completely distended, as in the latter case, owing to 

 the amount of injection in them, a degree of opacity is pro- 

 duced which renders the outline of many of the follicles some- 

 what indistinct. Most of the sections which I have ex- 

 amined have been made with a Valentin's knife, and the pre- 

 parations have been soaked for a short time in glycerine, 

 which facilitates the investigation of the pancreas, as of many 

 other animal textures, by increasing the transparency. 



The large excretory duct of the pancreas extends along the 

 centre of the gland from head to tail, and is enclosed on all 

 sides by the large lobules. From it, at frequent intervals, 

 smaller ducts proceed, which pass into these large lobules, 

 and in them divide and subdivide into fine branches, 

 for the ultimate lobules. Of these fine branches some 

 arise at right angles, others at a more or less acute angle, 

 and after a very short course they become connected 

 witli the ultimate gland follicles of the lobule to which they 

 belong. Each duct, as a general rule, preserves the same 

 calibre from the point at which it commences, to that at 



