540 SPECIAL HISTOLOGY. 



liar structure of the hepatic parenchyma, but also hj the small number 

 of the excreting canals. 



The bile is normally quite fluid, being only accidentally mixed with 

 cylindrical epithelium-cells, derived from the coarser biliary ducts. I 

 have never met with hepatic cells in them, and the statements of those 

 who have afiirmed their existence have arisen, either from a mistake, or 

 from confounding with them the polygonal cells of the epithelium of 

 the ductus interlobular es. Constitutents which, though abnormal, are 

 very frequent, are — fat-drops, coloring matter of the bile in granules 

 or granular masses, which, as in the hepatic cells, so also in the bile 

 itself, are occasionally abundantly excreted ; more rarely there are 

 crystals of cholesterine, and especially the reddish needles of bilifiilvin, 

 lately observed by Virchow ("Mittheil d. Wiirzburg, Phys. Med. Ges." 

 I. p. 311).* 



• [The view which Professor Kolliker takes of the mode of termination of the hepatic 

 ducts, can hardly be said to present any essential difference from tliat which Dr. Handheld 

 Jones has ably advocated in several successive papers in the " Philosophical Transactions" 

 (for 1846, 1849, and 1853), and which we here subjoin in his own words : — 



" The liver, in all vertebrate animals, may be regarded as consisting of a secretory 

 parenchyma and of excretory ducts. 



" The size of the excretory apparatus bears only a small proportion to that of the 

 secretory. 



" These two portions of the liver are not continuous with one another, bnt are disposed 

 simply in a relation of juxtaposition. 



" The action of the liver seems to consist in the transmission of bile, as it is formed, from 

 cell to cell, till it arrives in the neighborhood of the excretory ducts, by which it is absorbed. 

 This action is probably slow and very liable to be interfered with, contrasting remarkably 

 with that of the kidney, where a particular apparatus is added to insure completeness and 

 rapidity of action. 



" The secretion of the hepatic cells is very liable to be retained within the gland, either in 

 the cells or in a free state. 



"This circumstance, as well as its structural relations, seem to point out the liver as ap- 

 proximating to the class of ductless glands. 



" For the same reason it is highly probable that a part of the secretion of the cells is 

 directly absorbed into the blood which traverses the lobules" (" Phil. Trans.," 1849, p. 132). 



From an extensive series of researches in all classes of the Vertebrata, Dr. H. Jones comes 

 to the conclusion that the excretory system of the liver always terminates in closed tubes. 

 The ducts of the Sheep's liver, which in all essential particulars agrees with that of Man 

 and of the Pig, are thus described : — 



" In the minutest branches (of the biliary ducts) which seem to be approaching their 

 termination, and which can sometimes be examined and isolated in the most satisfactory 

 manner, the epithelial particles are remarkably modified ; they can scarcely be said to exist 

 as separate individuals, but rather their nuclei, which are often large and distinct, are set 

 close together in a subgranular or homogeneous basis substance. In ducts where this con- 

 dition of epithelium exists, there is seldom any distinct trace of basement membrane ; the 

 margin, though sufficiently even, yet exhibiting the bulging outlines of the component nuclei; 

 still less is there any proper fibrous coat, though the ducts may be more or less involved in 

 the filamentary expansions of the capsule of Glisson. Ducts of this character have usually 

 a diameter of about jg'jgth of an inch; they can sometimes be followed for a considerable 

 distance without being seen to give off any branches, or to diminish much in calibre. Their 

 mode of termination is various — several have been distinctly seen to terminate by rounded 



