Franklin P. Mall . 283 
grown sufficiently to favor the capillaries of the nodal point. Figure 49 
is from a more extensive injection of the hepatic vein with lamp-black 
gelatin. It is seen that the injected area, which is sharp, is angular in 
shape, with projections directed towards the nodal points. We have 
. here again the well-known picture of the beginning of passive con- 
gestion, which incidentally marks the portal units beautifully. 
Enough has been said to indicate that the growth of the lobule takes 
place at the nodal point. That does not mean that the cells multiply at 
this point, but simply that the new vessels, alternately portal and hepatic 
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Fic. 49. Tracing to show the extent of a granular injection of the hepatic 
vein. »% 40. The portal vein was first injected with blue gelatin and the 
thick granular lamp black gelatin was forced into the hepatic vein. The 
portal units are outlined as in chronic passive congestion. 
grow toward this point and break it into fragments to form new nodal 
points. In order to test this question a dozen sets of sections were made 
of the livers of growing rabbits and fcetal pigs with more or less satis- 
factory results. The rabbit which is a favorable object for this kind of 
study has a lobule of constant size (.6 mm.) from birth, until it is fully 
grown. In the pig the lobule measures .8 mm. in embryos 4 cm. long 
until a number of months after birth; in the adult they are 1.4 mm. in 
diameter. 
