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the center of the lobules nor at the nodal points. At the center of the 
portal units there is a very free communication between the blood capil- 
laries and the lymph radicals in the tips of the capsule of Glisson. So the 
lymph circulation is marked at this point, 7. ¢., the center of the portal 
structural unit, while in the rest of the unit it is insignificant or wanting 
altogether. 
’ 
RELATION OF THE BILE Ducts TO THE STRUCTURAL UNITS. 
All of our knowledge of the growth of the liver lobule indicates that 
the multiplication of the cells is in those portions of its periphery which 
mark the centers of the portal units. However, this statement is eXx- 
tremely difficult to prove. It is probable that the bile ducts communicate 
with the capillaries of the lobule throughout the whole length of the ducts 
of the sixth order, much as is the relation of the hepatic artery with the 
blood capillaries of the lobule, and unlike that of the portal vein, which 
gives rise to capillaries only at its tip. 
Much has been done to gain a clear understanding of the development, 
growth and regeneration of the liver cells, but the results are very meager, 
for only in rare instances are karyokinetic figures found in them. Fre- 
quently, however, cells with two nuclei are found and these appear to be 
scattered quite evenly throughout the lobule. I have studied many sets 
of serial sections of livers in all stages of development and have nearly 
always failed to find karyokinetic figures. In the few specimens in which 
cell divisions were present they were in groups of several hundred around 
the terminal bile ducts. MacCallum “ has also found a specimen in which 
there were numerous karyokinetic figures at the periphery of the lobule 
together with indications that the cells are being destroyed around the 
central vein. Ponfick* has shown that such figures are very numerous 
in the early stages of regeneration after removal of a large portion of the 
liver. In his specimens the dividing cells were found distributed evenly 
throughout the lobule which, on account of its erowth, has become much 
enlarged with a disarrangement of the radiating strands of cells. Recently 
Schaper” has discussed the question from a broad scientific standpoint 
and concludes that when the regeneration of the liver tissue forms typical 
lobules; the growth has taken place entirely within the minuter bile ducts. 
This conclusion is admitted by MacCallum ™ for only those cases in which 
4 MacCallum, W. G., Jour. Amer. Med. Assoc., 1904. 
© Ponfick, Vir. Arch., CXXVIII, Supplement, Heft., 1895. 
* Schaper, Arch. f. Entwicklungsmechanik, XIX, 1905. 
5 MacCallum, Johns Hopkins Hospital Reports, ».& 
