244 THE MICROSCOPE. 



minute in the blue dye, transfer it to alcohol for a few 

 seconds, and to absolute alcohol for a few seconds ; 

 remove it to oil of cloves, in which it should remain till 

 quite clear. It is now ready for mounting in benzole 

 balsam. 



For staining by a single immersion, add twelve drops 

 of the blue dye to seven of the magenta, and thoroughly 

 mix. Into this purple stain place the sections for about 

 a minute, then remove them to alcohol ; shake well for 

 a few seconds, and proceed as by the former method. 

 The magenta dye stains the woody fibre and vascular 

 tissue; the blue the parenchyma, cambium layer, and 

 medullary rays; while the pith and bark remain neu- 

 tral, or partake of both. 



In deciding upon which colour should be first em- 

 ployed, this will depend upon the particular structure 

 it is wished to bring out more forcibly than another. 

 To show the structure of the lamina use the blue 

 stain, because it displays the cell -walls far more dis- 

 tinctly than magenta. There is some difficulty in 

 fixing magenta, unless it is passed through benzole 

 and not oil of cloves ; benzole may, however, produce 

 an injurious effect upon the tissue. 



In using blue dye, no fixed time can be laid down 

 for immersion, this so much depending upon the 

 density or permeability of the tissue. Dr. Beatty 

 recommends that two solutions should be prepared a- 

 quarter and a half-grain solution, and that the leaf 

 should be transferred to the stronger if the staining is 

 not completed in the weaker in half an hour. There 

 is, however, one objection to this, that far too much 

 colour may be taken up in parts, and giving the 

 sections a very mottled appearance. Experience proves 

 that far better results are usually obtained by the 

 use of weaker dyes, although a longer time may be 

 required. 



As a general rule, sections should be left in the dye 

 till equally stained throughout, then remove them into 

 alcohol, brush the surfaces well with a camel-hair 

 pencil, and transfer them to absolute alcohol for a few 

 minutes, thence into oil of cloves till quite clear, and 



