200 ON FIXING THE ANILINE DYES. 



Stain rapidly and deeply in weak aqueous solutions, and stand 

 spirit well. Connective substances and the protoplasm of cells 

 are, in rapid staining, preferred by them to the nuclei, which, how- 

 ever, stand out on the stained ground very clearly. Phloxine is 

 the more beautiful and pleasant colour to work with. Both are 

 soluble in water or spirit, and weak solutions stain quickly. If 

 sections are placed in weak solutions for several hours, the nuclei 

 often take on the stain. Both these anilines are darkish red 

 powders by reflected light, Phloxine having a faint purple-crim- 

 son colour, and the colour of the solutions in a test tube will vary 

 with the strength. Murexide is a brownish-red powder, very 

 slightly soluble in cold water, not soluble in spirit, but readily so 

 in boiling water. On cooling and filtering, sections are immersed 

 for five or ten minutes, when it will be found to give a good 

 ground-stain for double-dyeing. With acetate of zinc it gives a 

 yellow stain. 



Maroon, phosphine, cerise, and mauve are all useful and 

 unused colours, phosphine yielding a good ground-stain of a rich 

 golden yellow, available with advantage for double-staining. The 

 rest resemble most of the other anilines in picking out the nuclei, 

 but they also stain the other structures. Dilute aqueous or alco- 

 holic solutions stain rapidly, and may be fixed by the process 

 described above, though phosphine holds very well of itself. 



Induline, which is also a new aniline colour, is a dark powder, 

 giving a pale bluish-purple stain. If used after carmine or picro- 

 carmine, the cell-body and intercellular substance will be preferred 

 by the induline, and the nuclei and connective fibres by the other 

 colours. It dissolves in warm water or dilute alcohol. Maroon, 

 phosphine, and cerise are new to histology. 



Any of the dyes mentioned by Mr. Reeves may be obtained in 

 small quantities from Mr. Cooper, chemist, Oxford Street, 

 London, W. 



