VI. SOME OBSERVATIONS ON THE STAINING OF 

 THE NUCLEI OF FRESH-WATER ALG^. 



Catherine Hillesheim. 



The material studied comprised several species of the com- 

 moner green algae collected in the stone quarries along the bank 

 of the Mississippi river near the university. 



Staining. — The only fixing agents tried were chromic and 

 picric acids. Various stains were used, such as hasmatoxylin, 

 fuchsin, anilin safranin, gentian violet, borax and ammonia car- 

 mine. Staining living cells with dahlia was unsuccessful. After 

 the material was stained and thoroughly washed, first in water 

 and then in the alcohols, it was mounted in glycerine jelly or in 

 formaline. The best results were obtained from the following 

 method : 



Chromic acid, 24 hours, 



Water, 24 " 



Alcohol, 10 per cent., 4 " 



Alcohol, 30 per cent., 4 " 



Alcohol, 50 per cent., 4 " 

 Borax and ammonia carmine (one half of each) , 4 days. 



Glycerine and water (5 per cent, solution), 5 minutes. 



The slide and cover-glass were then warmed and a small 

 drop of glycerine jelly placed in the center of the slide. When 

 this was melted the stained material was placed in it, the cover- 

 glass laid on and the whole put away to dry. When mounted 

 in formaline th$ preparation is ringed with Canada balsam to 



make it air-tight. 



Cell Staining. 



Sfyrogyra species. — The nucleus readily took on nearly all 

 of the stains mentioned. It was stained pink by the ammonia- 

 borax, carmine, fuchsin and aniline safranin. Hematoxylin 

 stained it blue. The nucleus was situated near the center of 

 the cell. It was much varied in shape in different species. 



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