152 Proceedings of the Royal Physical Society. 
rescent manner between two layers of peritoneum, so that the 
different lobules lie mostly on the same plane. Their investi- 
gation is on this account comparatively easy, even without the 
aid of any dissection.* 
Being engaged some months ago in making a series of pre- 
parations of the human pancreas for the sake of illustrating 
the structure of this gland to my microscopic class, I sue- 
ceeded in forcing an injection through the excretory duct into 
the ultimate follicles of the gland. I have been enabled in 
this manner to obtain, much more satisfactorily than by any 
other process, definite views of their relations to each 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 mixture of glyce- 
rine, spirits of wine, and water, in which Prussian blue, ob- 
tained 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, however, to 
make a complete injection of all the ultimate lobules through- 
out 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 exami- 
nation of those lobules into which the injection 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 
* See " Todd's Cyclopaedia," article Pancreas, 
