40 



the wall, while the other part, above and below, will retire to the 

 median line of the hair. The mucilage also contracts somewhat, 

 but otherwise remains unchanged. If the plasmolysis caused by 

 glycerin and sugar be interrupted at the proper time by the addi- 

 tion of water and the removal of the reagents, the protoplasm 

 expands again and resumes its activity. Chloriodide of zinc pro- 

 duces the contraction of the plasma and colors it yellow ; the 

 included mucilage becomes pale red or pink, the wall of the hair 

 blue, the membrane of the sac yellow, and the mucilage in the 

 sac faintly gray, of about the same tinge as the mucilage that has 

 escaped from the sacs. On application of iodine in potassic 

 iodide with sulphuric acid, the mucilage takes a reddish color. 

 The same color, only of a darker, brownish hue, is produced by 

 concentrated sulphuric acid. Vacuoles appear in the mucilage, 

 the plasma sac contracts and remains undissolved with the muci- 

 lage enclosed, while everything else, except the membrane of the 

 outer sac, disappears. Diluted chromic acid also stains the muci- 

 lage red. Caustic potash dissolves the mucilage rapidly, leaving 

 a network of protoplasm, which also soon disappears. 



Osmic acid (i%) stains the mucilage masses in the hair dark 

 blue, which soon turns into an intense black, and the plasma 

 layer becomes very light brown. In many of the sacs the muci- 

 lage assumes a blackish color, dark enough to make them almost 

 opaque, while in others it becomes only faintly gray, of about 

 the same tinge as the loose mucilage outside of the sacs. Bichro- 

 mate of potash in some cases causes the mucilage drops at first 

 to expand and dissolve, and then produces a deep orange-yellow, 

 finely granular precipitate ; in other hairs the mucilage masses do 

 not change their shape, but assume a uniformly deep orange hue. 

 Ferric chloride and sulphate give the tannin reaction for the 

 mucilage In the hairs, not, however, for that outside of them. 

 Acetate of copper and acetate of iron* also show plainly the 

 presence of tannin in the mucilage of the hairs; the latter salt 

 stains the mucilage in the sacs and outside of them a deep 

 orange-yellow. Strong sulphuric acid applied for a short time 

 after the acetates of copper and of iron, imparts to the mucilage 

 in the hairs and, in some instances in the sacs, an intense olive- 



*Cf. J. W, Moll, Maandblatt voor Natuurwetenschappen, I884. 



