306 FRANKLIN PARADISE JOHNSON 
more definite in livers of pigs of one, two, and three weeks. At 
two months it is as strongly marked as in the adult. These 
observations are in accord with those of Theopold (10), who 
states that the radial arrangement of the liver cells is first seen 
in pigs in the second half of the first week of postnatal life, and 
that the arrangement gradually increases in definition, although 
at the sixth week it is not strongly marked in all lobules. 
In pigs of three and four weeks old the hepatic lobules are 
still more strongly marked. The parallel rows of cells with the 
intervening layer of reticulum are still in evidence. In addi- 
tion, however, the reticulum in many places shows the addi- 
4 
4 
iS) 
Fig. 5 Portal injection of liver of a pig four days old, showing fewer and 
smaller sinusoids along interlobular septa. X 40. 
tion of delicate strands of collagen fibers (fig. 6), as demonstrated 
by staining by both Mallory’s and Bielschowsky’s methods. 
In certain places these fibers extend from portal vein to portal 
vein;.in other places they extend from one portal vein toward 
another, leaving, however, the nodal-point region devoid of 
them. From various degrees of this condition it is safe to con- 
clude that the connective tissue of the interlobular septa has 
its orgin in the connective tissue of the portal canals and grows 
outward from them, pushing its way into the reticulum already 
separating the lobules. According to Theopold (710), com- 
plete septa arising from connective tissue already present are 
in evidence, in certain places in the liver of a pig eight days 
