THE LIVER. 547 



this is, if I have observed riglitlj, the case in man, ^Yherc even in the 

 seventh week I did not succeed in clearly distinguishing free hepatic 

 columns. At other times, free terminations of the hepatic columns arc 

 apparently developed for a considerable period, perhaps until the whole 

 organ has nearly arrived at perfection, their formation appearing to 

 precede by some time that of new anastomoses, as is the case in the 

 Chick and other Birds, and according to J. ]Miiller, in a few Mammals ; 

 in the latter of Avhich, according to Mliller's figures, the hepatic columns 

 are grouped in lobes. These free, superficial hepatic columns may perhaps 

 throw some light upon the meaning of Weber's and Krause's statements 

 respecting the biliary ducts with coecal ends upon the surface of the 

 liver. With regard to the biliary ducts, they are assuredly nothing but 

 secondary excavations of a part of the primarily solid hepatic columns 

 and of the larger internal tracts, which border upon the original epithe- 

 lial diverticulum and which all consist of many series of cells. The ex- 

 cavation commences in the common biliary duct, proceeds towards its 

 branches, and must be considered to take place exactly as in other glands, 

 i. c. either by solution of the inner cells of the rudimentary structures, 

 or by the excretion of a fluid between them and the consequent produc- 

 tion of a cavity. In this mode of regarding the matter, there is only 

 one point for consideration ; viz., that according to Remak, all the 

 hepatic columns, even the largest, form anastomoses, whilst, as is well 

 knoAvn, the biliary ducts ramify without anastomosing. The only solu- 

 tion of this difficulty, consists in assuming that the anastomoses of the 

 primary, largest hepatic columns do not continue in the course of the 

 further development, but that they are re-ahsorhed, a process which has 

 its analogue in many phenomena of foetal growth. In Man alone 

 might we find an exception, for it seems to me that the anastomoses of 

 the right and left hepatic duct, in the/ossa hepatis, described by E. H. 

 Weber, are perfectly well explained by Remak's observations, and are 

 simply the embryonic anastomoses of the rudiments of these canals^ 

 which have attained to some, though no very great development. The* 

 mode of origin of the fibrous membranes of the biliary ducts becomes 

 readily comprehensible, if we reflect how the networks of hepatic columns 

 and the fibrous layers of the liver interdigitate ; so that layers of con- 

 nective tissue, &c., might be readily formed around the hepatic cylin- 

 ders from those elements of the fibrous layer which are nearest to them. 

 The further development of the vessels, nerves, &c., presents no difficul- 

 ties, taking place in the same way as in other organs. The gall-bladder 

 in the Chick, according to Remak, is a process, at first solid, of one 

 hepatic duct, which subsequently becomes hollow and rapidly increases 

 in size. I saw the folds of its mucous membrane, as early as in the 

 fifth month, in a human foetus.* 



* [In liis last memoir (Philosopbioal Transactions, 1S53), Pr. Handfield Jones maintains 

 that, in Fishes, Amphibia, and Birds, the liver is developed independently of the intestine, 



