118 SPECIAL HISTOLOGY. 



If, as results from the above analysis, the secreting pa- 

 renchyma of the liver consist of a solid network of hepatic 

 cells, one cannot but be struck with its great difference from 

 all the other glands of the body and the important question 

 arises, how, with this arrangement, the secretion is conveyed 

 from the interior of the cells, in which we suppose it to be 

 formed and finally carried away. Anatomy here gives no 

 sufficient reply; for although the ramifications of the hepatic 

 ducts have been traced accompanying the vena porta as far 

 as the hepatic islets, yet, as respects the connexion of their 

 finest twigs with the hepatic network of cells, no definite 

 answer has been afforded ; and indeed, up to the present time, 

 no satisfactory account even of the structure of the former has 

 been given. Without entering further, in this place, into the 

 distribution of the hepatic ducts, I will only observe, that in 

 carefully made microscopic preparations, we not unusually 

 find fragments of the finer and finest ducts, the ductus inter- 

 lobulares of Kiernan, between the hepatic islets, and readily 

 obtain evidence that they are constructed according to the 

 ordinary type of excretory ducts. The minutest of these canals, 

 which I have met with, measured -^" in diameter, possessed a 

 cavity of 0*0033'", and were composed of a simple layer of 

 common tesselated epithelium-cells, which were distinguished 

 from the hepatic cells by their small size (0*004 — 5"'), their 

 pale contents and the minuteness of their nuclei. I have fre- 

 quently met with such ducts as these ; they had no fibrous coat, 

 perhaps because it had been stripped off in preparing them ; 

 but occasionally they seemed to possess a membrana propria, at 

 least their external contours were sharply defined. Larger 

 canals, of 0004 — 0005"', always possessed a coat, and the epi- 

 thelium was more cylindrical, though not completely so, 

 inasmuch as the cells, with a breadth of 0*0048 — 0-0056"' 

 measured only 0*006 — 0*008'" in length. Often as I have 

 sought for a direct communication of the finest canals with 

 the hepatic networks, I have not yet directly observed it; 

 which is, indeed, by no means surprising, if we consider the 

 softness of the parts with which we have to do; but unfortunately 

 the result is a hiatus in the minute anatomy of the parts, 

 which can hardly be made good by hypotheses. As such, 

 however, I would offer the supposition, that the finest ducts 



