April 1902.] BOTANICAL SOCIETY OF EDIXBUKGH 233 



mount in xylol balsam. For rapid work, or in the case of 

 material very ditiieult to stain, the stock, or the 25 per 

 cent, solution, mav be used : the staining beiner then 

 carefully watched, and stopped when just right. 



The dilute solutions give very satisfactory preparations 

 of fungi, massive algae, liverworts, and lichens. (Sections 

 of SpJicrroholus, Peziza, Marcliantia, and Fucus were ex- 

 hibited.) 



The cell-membranes of some fungi are particularly well 

 stained, and in the case of fungal spores a selective action 

 is observed, some spores staining well, others not at all, 

 and the same differences are got with spores of the same 

 fungus at different ages. In liverworts, again, the walls 

 of the rhizoids stain very deeply, those of the thallus cells 

 less so. 



The best results were obtained with material fixed in 

 absolute alcohol, or in Bliss' fluid followed by absolute 

 alcohol. After Mann's fluid, corrosive sublimate, or picric 

 acid solutions, the results so far are not so good, but this 

 point, which is somewhat unexpected, requires further 

 investiofation. 



At the request of Mr. Eobertson, I take the opportunity 

 of adding to his communication to the Botanical Society 

 a description of the way in which the xylol blue stain was 

 prepared. It should be mentioned that the purpose for 

 which the stain was originally made was to provide a 

 rapid method of making a preliminary examination of 

 embryo-sections cut in paraffin. The use of the stain 

 for specimens to be permanently mounted is due to Mr. 

 Eobertson, and not to myself. 



After numerous experiments with various dyes and re- 

 agents, I found that by the following method a liquid 

 could be made which, at one and the same time, dissolved 

 the paraffin and stained and clarified the section. The 

 formula for the solution is as follows : — 



Sodium hydrate . . 1 grain. 



Toluidin blue ... 6 grains. 



Absolute alcohol . . 18 minims. 



Xylol . . . .600 minims. 



TRASS. BOX. SOC. EDIS. VOL. XXn. Q 



