189r..J MICROSCOPICAL JOUliJNAL. 383 



when considerable collections have been made and can- 

 not be examined for several hours. In such cases small 

 pieces of camphor-gum strewn in the water help to keep 

 the nlga3 from putrefying until they can be studied or 

 properly sorted and preserved. Formalin is useful also 

 for this purpose, but the acidity produced changes the 

 color quicker than is the case in camphorated water. 

 For preserving Cyanophycegp, camphor water keeps the 

 cell structure well if present in large volume, propor- 

 tional to the amount of material, but the coloring matter 

 is soon disolved. Chlorophycese, Phaeophycese and Rho- 

 dophycese, if well sorted and cleaned, are well preserved 

 in abundance of the fluid, even the finer details of cell 

 structure being preserved perfectly. But joerhaps the 

 most important use of camphor water is to preserve speci- 

 mens already fixed by other fluids. Specimens of the 

 larger Rhodophyceae, killed and fixed in concentrated 

 aqueous solution of picric acid are preserved to especial 

 advantage in camphor water; as one of us has experienced 

 in special work upon Rliabdonia tenera Ag. 



Summary of results. — CyanophycecB are best prepared 

 with a solution containing 1 per cent chrome alum and 

 one per cent formalin. This solution renders the gelat- 

 inous sheath aud matrices firm, keeps the cell contents 

 in a very natural condition, and retains in most cases the 

 colors in their ordinary tints. One to two per cent 

 formalin solution preserves the cell contents very well in- 

 deed, but does not keep the color well, or the softer gelat- 

 inoussheathaud matrices. Camphorwaterisnotvery favor- 

 able for many blue-greens. Many species must needs be 

 preserved in mass, and are associated with many bacteria 

 and the camphor solution is hardly strong enough to 

 wrestle successfully with the latter. 



Chlorophycece are very satisfactorily preserved in any of 

 these media. Chrome alum is to be preferred in most 

 cases, but some species are rendered very bri+tle as, e. g., 



