1882.] On the Structure of the Cells of the Liver. 



21 



nearly than any other. Klein described the liver-cells of mammals as 

 consisting of a protoplasmic network and of a hyaline interfibrillar 

 substance ; any apparent granules present he considered to be nodal 

 points of the network. In preparations made after Klein's methods 

 the granules are in fact with difficulty, or not at all, to be made out. 

 They are, however, very obvious in fresh teased or in osmic acid 

 specimens, especially in such specimens of the liver of the mole. 



Previous to Klein's account of the mammalian liver-cells, Kupffer* 

 described the liver-cells of the frog as consisting of a protoplasmic 

 network and of hyaline paraplasm. He figures the network as being 

 very irregular, with small granules in its bars, as being completely 

 absent from considerable portions of the cell, and as having much finer 

 meshes in the outer part of the cell around the nucleus. Kupffer's 

 observations were made upon the tissue treated with osmic acid or 

 with 10 per cent, salt solution and iodine. In sections of a frog's liver 

 hardened in osmic acid I find the cells to consist of a slightly stained 

 mass, in which granules and fat globules are imbedded. Treatment 

 with other reagents shows that this slightly stained mass really consists 

 of a network, and interfibrillar substance, the latter not in a granular 

 form, but occupying the spaces in the network unoccupied by the 

 granules and globules. If the liver is exposed for some time before it 

 is placed in osmic acid, the granules are no longer distinct; an irregular 

 network-like structure is formed out of them. This may possibly be 

 the network of Kupffer. Further, in the liver-cells of a healthy, hungry 

 (not fasting) frog the protoplasmic network stretches fairly equally 

 throughout all parts of the cell ; in winter frogs which have long 

 fasted (cf. below, p. 22) the network has wider spaces and thinner 

 bars in one part of the cell than in the other ; but then the wider 

 meshes are found in the outer, and not in the inner part of the cell 

 and are not absent from any cell region. Lastly, in osmic acid 

 specimens of such cells the outer parts appear homogeneous, except for 

 fat globules, the inner zone is crowded with distinct granules. 



Hence it is obvious that the network of protoplasm and the para- 

 plasm described by Kupffer do not in the least correspond to the net- 

 work of protoplasm and interfibrillar substance described by myself. 

 Whilst the liver-cells of all classes of vertebrates which I have exa- 

 mined have the above-mentioned common characters in the " resting" 

 state, they have certain minor distinguishing characters in each class, 

 depending chiefly upon the size of the cells and their nuclei, the posi- 

 tion of the nuclei, and the relative amount of the various cell- 

 constituents present. Of these, however, I do not propose to give an 

 account here. 



Hering, in 1867, pointed out that the liver in all vertebrates except 



* Kupffer, " Festschrift an Carl Ludwig," 1875. 



