1918-19.] BOTANICAL SOCIETY OF EDINBURGH 337 



but in the case of cultures intended for museum exhibition 

 I prefer to adopt a method that secures a moist atmosphere 

 over the cultures while at the same time the subaerial 

 mycelium is preserved in a thin layer of glycerine which 

 gives to the hyphal filaments a translucence that approaches 

 closely the appearance they have in the living culture. 

 In following out this modified method the procedure is 

 the same as that already described, up to the point when 

 tlie culture is adjusted on the support and is brought in 

 contact with it by the withdrawal of the excess water. 

 The support is then carefully dried round about the 

 culture. A preserving fluid made of equal parts of for- 

 maline, glycerine, and water is placed in small drops 

 around the edge of the culture just outside the limit of its 

 growth. This fluid runs under the culture and penetrates 

 the subaerial hyphae, but does not wet the surface or alter 

 appreciabl}^ the appearance of the aerial parts. An in- 

 verted watch-glass or a glass disk is now luted down with 

 gold size in the manner already described for dry prepara- 

 tions, but it is necessary to remember when covering such 

 preparations that the inside of the cover-glass should be 

 coated with a thin film of glycerine so that any con- 

 densation of moisture on the under side of the cover-glass 

 may not obscure the culture beneath it. It should also be 

 borne in mind that luting cements, as a rule, are rendered 

 less adhesive if the glass they are applied to bears even 

 a very thin film of glycerine, and precautions should be 

 taken to prevent the preserving fluid spreading from the 

 culture to those parts of the supports to which the sealing 

 cement will be applied. 



As supports for cultures, squares of glass, for most 

 purposes, are better than cards. They permit the back 

 of the culture to be examined, and with a glass support 

 one is able to use either transmitted or reflected light 

 when examining the culture under the microscope. 



TRANS. BOT. SOC. EDIN. VOL. XXVII. 24 



