THE PRESERVATION OF FRESH WATER 

 CHLOROPHYCEAE 



GILBERT MORGAN SxMITH 

 University of Wisconsiif, Madison, Wis. 



Although there are in existence several formulae for the preser- 

 vation of Chlorophj-ceae without destroying their natural color, 

 the results obtained by their use are generally unsatisfactor3\ 

 The two essential criteria for the success of a solution of this sort 

 are the retention of the natural color and the absence of plasmoly- 

 sis. In the work here reported on, an attempt has been made to 

 determine the efiicienc}' of the preserving mixtures which are in 

 general use, and also the effect of certain modifications in the con- 

 stitution of these mixtures. The preservative effects of certain 

 other new combinations were also investigated. 



Chromic acid and mercuric chlorid have proven very valuable 

 in cy tological work for fixation of algae without plasmolysis. The 

 solutions which I have used have contained these substances for 

 the preservation of the algae, and various copper salts for the reten- 

 tion of the color. For the chromic acid combinations, the chrom- 

 acetic mixture of Chamberlain^ was taken as a basis. This was 

 used in the following strengths with the different copper salts as 

 indicated. The capital letters preceding the name of the com- 

 pound refer to the abbreviations employed in tables I-III showing 



the results obtained. 



(1) CaCl/2 Chrom-acetic-cupric chlorid (half strength). 



Chrom-acetic mixture _ 50 cc. 



Water 50 cc. 



10 % cupric chlorid solution 10 cc. 



(2) CaCl/4 Chrom-acetic-cupric chlorid (quarter strength). 



Chrom-acetic mixture 50 cc. 



Water 150 cc. 



10 % cupric chlorid 10 cc. 



(3) CAS/2 Chrom-acetic-copper sulphate (half strength). 



(4) CAS/4 Chrom-acetic-copper sulphate (quarter strength). 

 ' Chamberlain, C. J. Methods in plant histology. 2d ed., 1905, p. 247. 



219 



THE PLANT WORLD, VOL. 16, NO. S, AugUSt, 1913 



