OBSERVATIONS ON STRUCTURE OF CELLS AND NUCLEI. 327 



manner deeply blue with haeniatoxylin. This is the reason 

 wiiy haematoxylin-staining does not yield such clear views of 

 the intranuclear, and especially the intracellular network of 

 fibrils, as carmine or picrocarmine, viz. because haematoxylin 

 stains the ground-substance of the cell too deeply, on account 

 of its containing mucin, and thereby these networks become 

 more or less obscured, whereas carmine or picrocarmine 

 leaves the ground-substance transj)arent and unstained, but 

 stains both the intracellular and intranuclear network. 



The intracellular fibrils and their network is best seen 

 in the slender goblet-cells of stomach (of newt) kept 

 for twenty-four hours in Miiller's fluid, placed then ior 

 about half an hour in a mixture of two parts of chromic 

 acid (^ per cent.) and one part methylated alcohol, washed 

 after this in water, and stained in picrocarmine. The fibrils 

 running in the long axis of the cell come out with remark- 

 able clearness ; if the upper part of the cell is inspected in 

 an oblique manner it is seen that the fibrils form a dense 

 network. In fig. 12 I have faithfully represented two such 

 cells. 



In the e})ithelial cells of the foregut that have retained 

 their cilia we recognise in the last-named specimens with 

 great clearness that the cilia pass into the cell- substance 

 through the cell-cover — hence the striated or granular ap- 

 pearance of this latter — and indentify themsehes ivith the 

 intracellular network of fibrils. Ebtrch, Marchi,^ and especially 

 Eimer^ have noticed a similar condition. 



Another point not less conspicuous, is the direct connection 

 of the fibrils of the intracellular with those of the intra- 

 nuclear network. In our preparations with 5 per cent, 

 chromate of ammonia this connection of the intranuclear net- 

 work, both witli the fibrils of the upper and lower portion of 

 the cell, is much more distinct than in specimens prepared 

 with Miiller's fluid, on account of the intranuclear network 

 being more clearly perceptible in the former than in the 

 latter. 



What I have stated with reference to the structure of the 

 epithelial cells mentioned sub a, applies likewise to those 

 mentioned sub b, c, and d, viz. tiiat we have to distinguish 

 in the cell-substance two parts, one the homogeneous 

 ground-substance and the other the intracellular network of 

 fibrils. This latter is in direct anatomical continuity with 

 the intranuclear network. But there exists a difiTerence in 

 the density of the intracellular network between the difterent 



' 'Archiv. f. Mikr. Anat.,' Bd. \v. 

 2 L. c, p. 115, figs. 3, 11, 20, and 21. 



VOL. XVIII. NKVV SER. Y 



