Franklin P. Mall . 293 
framework of the lobule is destroyed. Sections of the tips of the two 
systems of vessels show that more connective tissue extends to the periph- 
ery of the lobule along the portal vein than along the hepatic vein. How- 
ever, in nearly all animals it is not the entire lobule which is surrounded 
by an increased amount of connective tissue, but only that which marks 
the center of the portal unit. 
From the study of the connective tissue of the liver by various meth- 
ods, it is found that it is impossible to draw a line of separation between 
the interlobular and the intralobular tissues. One appears to be con- 
tinued into the other. However, there are stronger bundles which take 
a direct course toward the hepatic vein, not always following the capil- 
laries. These are the so-called radial fibers. More delicate fibrils com- 
municate with them and form a dense network around the capillaries. 
In general the fibrils radiate from the centers of the portal unit towards 
the nodal points as well as towards the terminal hepatic veins. They are 
of course arranged as are the capillary blood-vessels, which were discussed 
above. 
While the liver is growing it is evident that with the destruction and 
transformation of the lobules and portal units the reticulum must be con- 
stantly tearing and shifting. This is possible with such a delicate embry- 
onic tissue, and it may be that the connective tissue around the portal 
vein in a given stage lay within a lobule in an earlier stage. Veins of 
the third order are terminal in embryos about 2 em. long, 1. e., they are 
interlobular and intralobular, while later on these same veins become 
main trunks. In the pig’s liver there is no indication of any connective 
tissue capsule of the lobule before birth, and it probably does not appear 
until the liver is fully formed. Sections of the liver of pigs two months 
old show the lobule outlined by marked bands of cell radiating from the 
centers of the portal units to the centers of the nodal points. Possibly 
at this time the reticulum between the lobules is a little denser than that 
within the lobule. However this may be, the capsule of Glisson is but 
slightly marked, having within it but few nuclei of connective tissue 
cells. It is evident that the connective tissue of the liver must be studied 
anew from the standpoint of an ever-changing lobule during development. 
THE LYMPHATIC Ducts. 
Hand in hand with the development of the capsule of Glisson, the 
lymphatic ducts grow into the liver. According to Professor Sabin, they 
arise from the receptaculum in embryo pigs and grow along the trunks 
of the artery and portal vein. How rapidly they grow and function has 
