394 
DR. LIONEL BEALE ON THE 
hepatic cells, but usually ceases at the point where the narrow duct expands into the 
wide secreting tubes of the network. In a few instances I have seen tubes contain- 
ing liver-cells lined with this delicate epithelium, observations which confirm those 
of Mr. Wharton Jones, who has seen hepatic cells in the smaller ducts. In these 
cases the cells may have accidentally entered the ductal portion of the tube. 
The arrangement above described is very similar to that which occurs in the gastric 
gland. It is only in the lower part (stomach tube) that the cells of spheroidal epithe- 
lium (which alone there is every reason to believe take part in the secretion of the 
gastric juice) are found. The upper portion or duct (stomach-cell) is lined with 
columnar or subcolumnar epithelium*. The secreting cells are not arranged with 
any order or regularity round the basement membrane of the tube, as in the kidney, 
but appear to fill its cavity; so that the secretion having escaped from the cells with 
or without their liquefaction, must pass off by the slight interstices between them. 
As I have before remarked, the same irregularity occurs in the arrangement of the 
secreting cells in the tubular network of the liver, and as may be observed in a less 
remarkable degree, in the secreting portion of many other glands, as the pancreas, 
lacteal glands, sebaceous and sweat glands. 
The conclusions to which I have been led from my observations, may be summed 
up as follows : — 
1. That the liver of vertebrate animals essentially consists of two “solid” tubular 
networks mutually adapted to each other. One of these networks contains the liver- 
cells, the other the blood. 
2. The cell-containing network is continuous with the ducts. The small delicate 
epithelial cells lining the latter channels contrast remarkably with the large se- 
creting cells, which are not arranged in any definite manner within the tubes of the 
network. 
3. The duct is many times narrower than the tubular cell-containing network at 
the point where it becomes continuous with it. 
4. Injection passes sometimes on one, and sometimes on the other side of the tube, 
or between the cells, where two or more lie across the tube. As injection can thus 
be made to pass readily from the ducts into the network and around the cells, it 
follows that there can be no obstacle to the passage of the bile along the same 
channels in the opposite — its natural direction. 
5. In sotne animals, the most minute ducts are directly connected with the tubes 
of the cell-containing network. Of these branches, some pass amongst the most 
superficial meshes to join the network at a deeper part. In other animals the finest 
ducts form a network which is continuous with that in which the liver-cells lie. 
6. The interlobular ducts do not anastomose, but the branches coming oflf from 
the trunk are often connected with each other, as well as with the parent trunk, near 
their origin from it, by intervening branches. 
* Todp and Bowman’s Physiology, vol. ii. 
