79 



Acetic Alcohol as a Killing and Fixing Agent in Plant 



Histology. 



By F. L. Pickett. 



Tiie wiiter has foiUKl a solution of 5-S9c of glacial acetic acid in 

 absolute alcohol a siileudid killing and fixing agent in preparing histologi- 

 cal material. For the best results the alcohol should be heated to its boil- 

 ing point on, the water bath before the addition of the acid and specimens. 

 For large pieces of stems with well developed wood, the tixing agent is 

 ju'epared in a flask and is allo\\-ed to boil after the specimens have been 

 placed in it. Tight corking of the flask and immediate cooling causes the 

 withdrawal of air from ves.sels and si^aces and allows immediate penetra- 

 tion of the reagent. The acid should be washed out with three or four 

 changes of alcohol and then the specimens imbedded in paraffin in the 

 usual manlier. Hard specimens should be washed in alcohol and then be 

 placed in a mixture of three parts S0% alcohol and one part glycerine for 

 preservation. 



This solution has been used successfully with leaves, rust, stems, 

 enilu'yos in situ. It has the advantage over alcohol alone of causing less 

 shrinking and of flxing cell contents quite well enough for this line of 

 work. .Specimens are not discolored by precipitates, as is often tlie case 

 with chromic acid mixtures ; and much time is saved by the elimination 

 of long \Aasliing in water and dehydration before imbedding. 



