284 A Study of the Structural Unit of the Liver 
Tn the set of rabbits’ livers, hardened in a variety of ways, at was found 
that whenever the distance between two adjoining portal veins is consid- 
erably greater than the average diameter of a lobule, a small portal vein 
grows into the nodal point which separates them. The same is true re- 
garding the hepatic veins as shown in Fig. 50. From all appearances, the 
hepatic branch, 4, is a recent one, growing into the large nodal point 
which had pushed apart the hepatic veins 7 and 5. No doubt earher in 
its development, the whole field of this figure formed one nodal point, and 
Fic. 50. Section of the liver of a rabbit one day old. x 85. Hardened in 
Flemming’s solution. P, portal branch; h, hepatic branch; n, nodal point; 
1, 2, 3, 4, order of growth of the vessels; the next vessel will appear at 5, and 
then it will grow towards the nodal point 6. 
then the hepatic vein, 7, grew into it. This was followed by portal veins, 
2, then 3, then by hepatic vein 4. Ata later stage the portal vein, 2, will 
send a branch into nodal point 6, and so on. In a measure, we can corner 
a bit of liver tissue at the junction of two main stems, as shown in Figs. 
‘51 and 52. It is fair to assume that the tissue at this angle grows with 
the rest of the liver, for a time at least, and that the small vessel arising 
from the portal in Fig. 51 and that from the hepatic in Fig. 52 are new 
