Brera of the Human Liver. 79 
about 345 of an inch thick—introduced into one of the finer 
branches of the vessel to be examined. This done, the branch con- 
taining it is carefully dissected with the assistance of a loupe— 
magnifying about 3 diameters—and then removed, together with 
a small portion of the parenchyma adhering. After the removal 
of the probe, the fragment—on a glass slide and supplied with 
plenty of water —is placed on the dissecting stage, and the vessels 
freed from the surrounding parenchyma by a neat dissection with 
fine curved needles, under a loupe magnifying about 8 to 10 
diameters and by transmitted light. During the dissection, the 
water should be constantly changed, and the preparation be kept 
immersed. The vessel being dissected, as far as possible, under 
this low magnifying power, the preparation is now covered by a 
piece of thin glass, and ready for study with the higher powers of 
the compound microscope. ‘To obtain satisfactory results, many 
such dissections must be made, and the investigator should be pro- 
vided with plenty of patience and perseverance. The finer branches 
of the artery can readily be distinguished from those of the portal 
vein by their smaller diameter and the greater thickness of their 
walls ; also by the presence of small oblong nuclei, which disappear 
in the finer branches of the portal vein. The walls of the finer 
branches of the hepatic veins are stronger than those of the portal 
vein. In such preparations, if carefully made, the transitions of 
the finest branches of the vessels into the capillaries can easily be 
studied. 
The capillaries of the parenchyma have nothing peculiar in their 
structure, by which they might differ from those of other organs ; 
their diameter ranges from zodoo tO yo#o0 of an inch; the average 
iS zoo0 Of an inch. They can conveniently be studied by taking 
a very small fragment of the parenchyma, placing it on a glass 
shde, and—being well covered with water—loosening the texture 
by means of fine needles, but without tearing it too much. This 
is done by transmitted light on the dissecting stage, and under a 
loupe, magnifying from 8 to 10 diameters. Thus properly pre- 
pared and washed, it is covered by the thin glass and ready for exa- 
mination with a higher power. Care must be taken that there is 
sufficient water on the slide to prevent the covering glass trom pres- 
sing too hard upon the preparation. 
Commencement of the finest branches of the Hepatic Ducts and 
Lymphatics in the Network of “ Biliary Tubules.” 
Independent of the capillary network which forms the connect- 
ing link between the finest branches of the portal vein, hepatic 
artery and hepatic veins, there exists another in the parenchyma 
of the liver, from which the finest branches of the hepatic ducts and 
lymphatics arise, to proceed toward the exterior of the organ. To 
