Staining Paraffin Sections 75 



found to be destained too much, it can be run back into water and 

 mordanted and stained again. As in some other staining combinations, 

 restained preparations are seldom as clear in detail as slides stained 

 correctly the first time. 



THE CRYSTAL VIOLET-IODINE STAIN 



The next stain to be considered is another cytological stain. It is 

 included here because it yields preparations that are valuable in the 

 teaching of some topics. In teaching mitosis at the elementary college 



STAINING CHART VII 



Crystal (Gentian) Violet-Iodine 

 Pre-Staining Operations as in Chart I 



resin and 



IKI 



15 min. 



rinse in water 



i 

 crystal violet 

 1-4 hr. 



i 

 rinse 



i 

 IKI 

 15 min. 



} 

 rinse 



i 

 50% alcohol 

 picric acid 

 30 sec. 



i 

 95% 

 alcohol 

 10-60 sec. 



cover glass 



t 

 xylene III 



t 

 xylene II 



t 

 xylene I 



t 

 examine 



t 

 1/^ absolute alcohol 



14 xylene 



[_ 1/3 cedar oil 



30-60 sec. 



t 

 absolute 



alcohol II 



30 sec. 



t 

 absolute 



alcohol I 



30 sec. 



level, most teachers prefer longitudinal and transverse paraffin sec- 

 tions, stained to show cell walls and tissue organization as well as the 

 more prominent features of nuclear division. Crystal violet stains the 

 chromosomes a brilliant blue-black, on a colorless, almost invisible, 

 cellular background. Such preparations are a valuable supplement to 

 the standard classroom slide. 



The procedure given in staining Chart VII is but one of the 

 numerous variants of the process. Probably no other staining pro- 

 cedure is as responsive to the individual touch of the technician, and 

 a specific procedure should be regarded as a point of departure for 

 developing a personal routine. 



