436 EXCRETION. 



of uniform size, about T ^oo of an inch in diameter, which surround the liver-cells, each 

 cell lying in a space bounded by inosculating branches of these canals. This plexus is 

 Entirely independent of the blood-vessels, and it seems to enclose in its meshes each indi- 

 vidual cell, extending from the periphery of the lobule (where it is in communication 



with the interlobular bile-ducts) to the intra- 

 lobular vein in the centre. The vessels prob- 

 ably have excessively thin, homogeneous 

 wa lls although the existence of their mem- 

 brane has not been positively demonstrated 

 and are without any epithelial lining, being 

 much smaller, indeed, than any epithelial 

 cells with which we are acquainted. This 

 arrangement, as far as is known, has no ana- 

 logue in any other secreting organ. 



Although it is within a few years only 

 that the reticulated bile-ducts of the lobules 

 have attracted much attention, they were dis- 

 covered in the substance of the lobules, near 

 the periphery, by Gerlach, in 1848. It is evi- 

 dent, from an examination of his figures and 

 description, that he succeeded in filling with 

 injection that portion of the lobular net-work 

 near the borders of the lobules, and he demon- 

 ters. (Koiiiker.) strated the continuity of their vessels with 



b, b, &, capillary blood-vessels ; g, g, g, capillary bile- , . ,-,-, -, i ., -i j i 



ducts; l, I, I, liver-ceils the interlobular ducts ; but he did not recog- 



nize the vessels nearer the centre of the lob- 

 ule. It is now demonstrated, beyond a doubt, that there are either canals or interspaces 

 between the liver-cells in the lobules, and that these open into the interlobular hepatic 

 ducts. It is still a question of discussion, however, whether these passages be simple 

 spaces between the cells or true vessels lined by a membrane ; but this point has no great 

 physiological importance, and we can readily imagine that it would be exceedingly diffi- 

 cult to demonstrate a membrane forming the wall of a tube, the whole measuring but 

 nr^rfr of an inch. 



A peculiarly favorable opportunity for observing the bile-ducts in the lobules was 

 presented in the livers of animals that died of the so-called " Texas cattle-disease." This 

 was taken advantage of by the late Dr. R. C. Stiles, who was able to verify, in the most 

 satisfactory manner, the facts which have lately been established by the German anato- 

 mists. In these livers, the finest bile-ducts were found filled with bright yellow bile, 

 and their relations to the liver-cells were exceedingly distinct. In the examination of 

 these specimens, the presence of what appeared to be detached fragments of these little 

 canals is an argument in favor of the view that they are lined by a membrane of exces- 

 sive tenuity. These interesting anatomical points were demonstrated by Dr. Stiles before 

 the New York Academy of Medicine, and we have since been able to verify them in every 

 particular. 



Anatomy of the Excretory Biliary Passages. There can be scarcely any doubt of the 

 connection between the intercellular biliary plexus in the substance of the lobules and 

 the interlobular ducts. We shall see, farther on, that the ducts, in their course from the 

 lobules to the intestine, are provided with numerous small, racemose glands, which prob- 

 ably secrete a mucus that is mixed with the bile ; but, in all probability, the peculiar 

 elements of the bile are formed in the lobules, and the canals situated between the lobules 

 and leading from them to the larger ducts are merely excretory. 



Between the lobules, the ducts are very small, the smallest measuring about ^^ of 



