120 
DR. C. H. JONES ON THE STRUCTURE 
scanty basis substance ; they are quite devoid of basement membrane, and measure 
s' - 3^0 0 0 th of an inch towards their terminal extremity. The mode which I have 
adopted of examining the ducts may be thought by some to be objectionable, on the 
ground that the extremities of the ducts must necessarily be lacerated ; but I think a 
careful repetition of the process I have indicated, will satisfy the observer that it 
offers the most probable means for deciding the point in question ; in fact I know of 
no other except injection which can be adopted, and I am satisfied that in this case 
the results of injection are not to be depended on. To one remarkable character of 
the ducts which has been mentioned I would ask especial attention, viz. the long 
course which the smaller ramifications take without giving off branches. I have ob- 
served one which ran ^th of an inch without giving off any branches, and another 
which gave off only one branch in a course of -^oth of an inch. When we take into 
consideration this fact, and remember also how minute the terminal extremities of 
the ducts become, and that they are not unfrequently seen distinctly closed, it will 
appear quite certain that the ducts can have no actual connection with the surround- 
ing parenchyma, so as to envelope and contain it in their terminal expansions, as 
some have supposed. The real relation of the ducts to the parenchyma is, I think, 
well shown by a peculiarity in their condition which I have noticed as of tolerably 
frequent occurrence ; when this exists there are found in the parenchyma numerous 
masses of more or less deep biliary tinge, consisting apparetitly of large yellow gra- 
nules enclosed in an envelope ; when a duct is dissected out, these yellow masses are 
found adhering to it at various parts of its circumference ; they are manifestly not 
in the cavity of the duct, but simply adherent to it. That these yellow masses origi- 
nate in the secreting parenchyma is I think indubitable ; they evidently consist of 
biliary matter ; but this seems to have undergone some change, which has rendered it 
incapable of being readily absorbed by the ducts, and it thus remains on the exterior, 
indicating as it were the route it would normally pursue. I may here describe some 
remarkable structures which I have found in the liver of the Skate {Raia Bails), and 
respecting which 1 am rather in doubt whether they belong to the parenchyma or the 
ducts ; these are vesicles of oval or subcircular form, measuring from to 3 ^th of 
an inch in diameter ; they have a distinct envelope of homogeneous membrane, and 
a central cavity, which does not occupy more than half the diameter of the vesicle ; 
the intervening substance between the wall and the cavity presents no distinct struc- 
ture, but only some traces of concentric layers with a few nuclear corpuscles ; the 
aspect of the vesicles is such as to imply that they are filled with some substance 
having a high refractive power, which is probably of oily nature, derived from that 
which is so abundantly diffused throughout the parenchyma. These vesicles are 
often found free, and unconnected with any other structures; they appear to be 
scattered throughout the parenchyma, but are sometimes at least involved in the 
fibrous sheaths of the ducts, so as to remain adherent to them ; what their function 
may be is quite hypothetical ; I can only conjecture that they may serve as reser- 
