204 BOTANICAL GAZETTE. 



structure for the dyes they attract enough(even in a weak solution) to make 

 theiii black and opaque. Ordinarily the logwood dye is used alone, 

 but there are cases, as in the fruiting fronds of ferns, where we may remove 

 the specimen from the logwood and wash it hastily in a couple of waters 

 to remove any alum crystals which may have formed on it, and then place 

 it in pure alcohol(or nearly pure) which is just fairly tinged with iodine 

 green (aniline), where it may remain for twenty-four hours or more and 

 come out with the frond scarlet, the sporangium brown or brownish-black 

 and the spores bright grass green. An object fit for ecstasy if one have 

 a binocular microscope! If he do not have, we can only pity him., 



It sometimes happens that plants which have a glaucous color do not 

 bleach out so well as to stain evenly in logwood dye. I have found 

 that a prolonged soaking in alcohol would usually remove the trouble. 



Now as for the more usual double staining. Here one may have a choice 

 of colors. I will for present purposes give only two; as the principles 

 involved in the use of these would guide in the use of the others; and I will 

 give those which in my own work have given me the greatest satisfaction. 



Ammonia Carmine made after the formula of Dr. J. J. Woodward 



is: 



"Pulv. Carmine, 7^^ grains. 



Water of Ammonia, . .30 drops. 



Absolute Alcohol, i^ ounce- 

 Glycerine 1 ounce 



Distilled Water, 1 ounce. 



Put the pulverized carmine in a test tube and add the ammonia. 

 Boil slowly for a {q\v seconds and set aside, imcorked, for a day, to get 

 lid of excess of ammonia. Add the mixed water and glycerine and 

 next the alcohol; then filter." 



The other dye I would indicate as the iodine-green. Of this I keep 

 a strong alcoholic solution on my table. Let it be a dark green in strength 

 and it can be weakened to suit the purposes in each case. 



Now for the method of using it. Taking the specimen, bleached or un- 

 bleached, from the alcohol where it has been "clearing up," I put it in fresh 

 alcohol and to this add enough of i he iodine-green solution to give a faint 

 green tinge. Two or three drops in a tablespoonful will suffice ordinarily. 

 This I set away for 12 to 24 hours as the case may be. Examining it after this 

 lapse of time I find the alcohol has appreciably cleaned up. That is, portions 

 of the plant structure have taken it from the solution. Moreover, and very 



