Criteria of Successful Processing 115 



It is probable that undue blame has been placed on the killing 

 fluid for the distortion of protoplasts of these large sporocytes. Recent 

 developments in dehydrating and infiltrating methods indicate that 

 these processes contribute much to the quality of the image. Raj)id 

 dehydration is probably one cause of distortion. 1 he slow dehydration 

 obtained by the glycerin evaporation method yields a very high ratio 

 of well-preserved ovules. The mild dehydrating action of such paraflFin 

 solvents as the butyl alcohols and dioxan minimizes distortion of 

 large sporocytes. It is probable that a properly balanced killing fluid, 







^J^jm I "^ . .'^'Ite'i"^ "^ 



Fig. 11.4— Comparison of fixation in large megasporocytes of Lilium: a, L. um- 

 bellatum, Allen-Bouin III, 12 days, glycerin dehydration to alcohol-xylene; b, L. 

 speciosum, Bouin, alcohol-xylene; c, L. tigrinum, Allen-Bouin II, 6 months, acetone- 

 xylene; d, L. tigrinum. first division of meiosis. Allen-Bouin II, 6 months, acetone- 



xylene. 



