382 Royal Society. 



presence of free nuclei in granulous matter indicates an active change 

 to be proceeding in the part. In the second condition sometimes 

 observed the granulous matter lies imbedded in it, a varying number 

 of pellucid vesicles of great delicacy, but quite distinct ; these testify 

 that a process of active growth takes place in the minute ducts, and 

 show, the author thinks conclusively, that these minute ducts are 

 not mere efferent canals. 



Sugar was detected on two or three occasions in the livers of 

 fishes ; it seems to be absent when the organ is extremely fatty. 



In the minute hepatic ducts of reptiles, the condition of the epi- 

 thelium is very similar to that in fishes; the nuclei sometimes ap- 

 pearing with great distinctness, sometimes being obscured by much 

 granulous matter, sometimes developing themselves into pellucid 

 vesicles. The livers of frogs and toads almost constantly contain 

 dark yellow masses which were formerly regarded by the author 

 as biliary concretions, but are now considered to be only pig- 

 mentary deposits ; they coexist sometimes with much diffused black 

 matter. 



The ultimate ducts have been traced recently very satisfactorily 

 in Birds, Mammalia and Man, and the description given of them in 

 the paper accords with the author's former account. 



The development of the liver and its apparatus of ducts has been 

 traced out in fishes and reptiles, and the following results obtained 

 in both classes. 



(1.) The liver (i. e. the parenchyma of the organ) is formed as an 

 independent mass, and does not proceed as an effect from the in- 

 testine. 



(2.) The gall-bladder is developed separately as a transparent 

 vesicle, containing a clear fluid. 



(3.) The gall-bladder elongates itself at one end, tends towards 

 the intestine, and at last opens into it, while from one part of its 

 extent hepatic ducts are developed ; in the Frog the hepatic ducts 

 seem, however, to be formed at the same time as the gall-bladder, 

 and to be developed pari passu along with it. The cystic duct is 

 lined by ciliary epithelium which plays very actively. 



The examination of the process of development in the chick has 

 confirmed, so far as it was carried, the account given in the former 

 paper. 



In Mammalia the subject of inquiry has been chiefly the follow- 

 ing, viz. to ascertain how far there was evidence that the secretion 

 of bile actually is effected in and by the hepatic cell, or whether its 

 presence in them is accidental, and the bile is really and necessarily 

 secreted by the ultimate ducts. 



It is remarked that the existence of a portal vein conveying blood 

 from the intestinal surface is coeval, not with the formation of a 

 bile- secreting structure (for many animals have organs which 

 secrete abundance of biliary matter without any portal vein), but 

 with the addition of a parenchymatous mass to the biliary organ, to 

 which mass exclusively the portal vein is distributed. It is known 

 that the parenchyma of the liver during, and for many hours after, 



