100 Botanical Microfechnique 



vapor and the solution are higlily irritating and poisonous. j)ioducing 

 persistent skin and pulmonary disorders. Materials that ha\e been 

 stored in strong formaldehyde should be rinsed in Avater if used for 

 prolonged study. 



An improvement over formaldehyde for the preservation of algae 



is the following: 



Water 93 cc. 



Formaldehyde (U.S.P.) 5 cc. 



Glacial acetic acid 2 cc. 



Hydrodictyon and Spirogyra stored in this fluid for 5 years were 

 found to be in excellent condition for whole mounts in Avater. A 

 further improvement is to add glycerin. 



Water 72 cc. 



Formaldehyde (U.S.P.) 5 cc. 



Glacial acetic acid 8 cc. 



Glycerin 20 cc. 



This is one of the best preservatives for unicellular, filamentous, 

 and even the larger bulky algae, for fleshy fungi, for liverworts, and 

 for mosses. A trace of fast green dye imparts enough color to minute 

 or transparent subjects to make them more readily visible under the 

 microscope. The material should be mounted on a slide in a drop of 

 the preservative. Fhe volatile ingredients soon e\aporate, but the 

 glycerin prevents drying of the preparation during a long period oi 

 study. Liverwort thalli can be removed from the iluid and placed in 

 a watch glass for study. The thalli of Marchantia, for example, are so 

 firm that the gametangial disks stand upright in a normal position. 

 The glycerin keeps the material moist for hours, and specimens can 

 be returned to the stock bottle uninjured. 



The natural colors of plants can be ])reserved in one of several 

 fornudas. The simi)lest formula for green plants consists of one of the 

 lAA formulas with (()pj)er sulphate added (lilaydes 19:^7). Ihe 

 following formula is usually satisfactory: 



Water .85 cc. 



C;oi)])er sulplialc 0.2 g. 



When completely dissohed, add 



Glacial acetic acid 5 cc. 



Formaldehyde (U.S.P.) 10 cc. 



Flhvl alcohol (95'/f) .50 ^x. 



