79 



Acetic Alcohol as a Killing and Fixing Agent in Plant 

 Histology. 



By F. L. Pickett. 



Tiie writer has found a solution of 5-S9o of glacial acetic acid in 

 absolute alcohol a splendid killiriL!: and tixing agent in preparin'.; histologi- 

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

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

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

 ])repared in a flask and is allowed to boil after the specimens have been 

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

 withdrawal of air from vessels and spaces and allows immediate penetra- 

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

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

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

 placed in a mixture of three parts S0% alcohol and one part gl.vcerine for 

 preservation. 



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

 embryos in situ. It has the advantage over alcohol alone of causing less 

 slirinking and of fixing cell contents quite well enough for tJiis line of 

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

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

 of long washing in water and dehydration before imbedding. 



