BOTANICAL GAZETTE. 203 



of the specimen and on the quantity of chlorophyll to be removed. 

 As between the bleached and unbleached specimens, necessity may 

 compel the bleaching, but never bleach when you can avoid it and still 

 make a good specimen. 



From this point the treatment of the bleached and unbleached specimens 

 is the same, and the only question is as to the staining fluid: what one, 

 or whether more than one. I give this as a general rule: if you are to use 

 but one, let that one be the Hcemaioxylin Dye. My reasons are first, it 

 is permanent: second, it is clear and beautiful; third, you can produce with 

 It almost any shade from a deep, almost black-brown, to the sliglitest tinge 

 of red; fourth, if by accident you obtain too deep a shade you may more 

 satisfactorily remove part of it than of any other dye. This is done by 

 placing the object in, say a tablespoonful of alcohol, and to this add a 

 few drops of bichloride of tin. In a few minutes (often in a few seconds) 

 the alcohol will be colored by the dye extracted and the object be by so 

 much the lighter colored. It is besG, however, not to allo-v the speci- 

 men to remain in too long, or it assumes a dead hue instead of the vivid 

 color which it first assumed when immersed. 



I give the formula I find in Dr. Beatty's article, republished from Science 

 Gossip into the American Journal of Microscopy, June, 1876, and here 

 would also state how much I am indebted to the article, both for my 

 own methods of staining and for the facts of this contribution. 



Take "Ground Campeacby Wood, J^ ounce. 



Pulv, Alum, 1 ounce. 



Mix and triturate in a mortar for twenty minutes, then add five ounces 

 ot hot, distilled water and let it stand for two days. Filter, and to 

 each ounce of the dye add two drachms of 75 per cent, alcohol. In twenty 

 four hours again filter to remove the precipitated alum." 



I would add ihat all the dyes can be obtained from any respectable 

 optician in our large cities and that it is cheaper to buy than to make them. 



In using this, I take the requisite quaniity of wa'er to immerse the 

 specimen and add to it just enough of the dye to give the shade I desire, 

 then if but little of the dye was used I add a very little (say 4 per cent. ; 

 of powdered alum to the water. This i% not always or even usually necessary. 

 Then after mixing, for a moment, the dye and the water I immerse the 

 object in it. How long shall it stay there? Until it has done its work. 

 Sometimes, as in some sections, this will be in a few minutes; in other 

 cases it may be hours. Bear in .mind, however, that the specimen is to 

 be watched, lest r wing to an affnity of certain portions of the plant 



