and Laboratory Methods. 



1887 



solution containing 1 or 2 per cent, of formalin and enough copper acetate 

 or copper sulphate to give the solution a strong greenish tint. This solu- 

 tion acts upon the chlorophyll to form copper phyllocyanate, which is insoluble 

 in all preserving fluids except strong alcohol. At the end of two or three days 

 the specimens will have assumed a dark blue-green color ; they should then be 

 removed and cleared in a dilute solution of glycerine and formalin which con- 

 tains no copper salts, until the desired shade of green is reached, when they 

 may be transferred immediately to the permanent preparation jars. 



The most satisfactory style of museum jar is that shown in the accompanying 

 figures ; it is a rectangular, crystal glass jar with one polished side, the cover is 

 ground and fitted to the jar. The usual sizes in which these jars can be obtained 

 are 2.3 x 15x 8 cm., 21 x 13 x 5.5 cm., 16 x 10 x 8 cm., and 12.5 x 9.5 x cm. Such 



Fig. o. — Cydonia Japonica. Showing 

 stipules. 



Fig. 6. — Dictyophora ravenelii. 



a jar is much better adapted to the use of plates for backgrounds than a cylin- 

 drical jar, besides obviating any contortion due to curved glass surfaces. 



When a jar of the proper size has been selected, a suitable plate is cut for a 

 background upon which to mount the specimen ; this plate should be of such a 

 height that it cannot rock backward and forward when the cover is on the jar, 

 preferably it should be either of black or of milk glass, according to the color or 

 transparency of the specimen to be placed upon it. The plate being laid in a 

 shallow dish of water, the specimen is laid upon it and tied with silk thread of the 

 same color as the background. The value and beauty of the preparation will 

 depend largely upon the operator's skill in arranging the specimen on the plate; 

 constant attention must be paid to the nature of the material, the facts to be illus- 

 trated, and the symmetrical arrangement of specimens. The jar is nearly filled 

 with a 3 per cent, solution of formalin into which the plate bearing the specimen 



