A New Mitotic Structure. By E. Sheppard. 



119 



stain is being discharged by the second bath in the iron solution. 

 This latter should be about one-sixth to one-eighth of the strength 

 of the mordant, in order that it may be slow in action. Take 

 plenty of time and use careful judgment, examining the sections 

 from time to time under the Microscope. When satisfied that 

 the correct stage has been reached, wash carefully in gently 

 running tap-water for about a quarter of an hour to twenty 

 minutes. The sections on the cover-glass are now dipped once 

 or twice in upgrade alcohols 30, 50, 70, 90 p.c, differentiating the 

 methyl-blue in the last grade of spirit when necessary. This must 

 be done very carefully and to a great nicety, and under a not less 

 than ^-in. objective. 



This latter remark applies equally when the differentiation of 

 the hematoxylin is being effected. 



Upon the completion of the differentiation, the sections are 

 transferred direct into oil terpineol and allowed to remain about 

 10 minutes, or until perfectly cleared, and then mounted in 







Fig. 15. 



paroleine. Although the methyl-blue stain is not permanent in 

 paroleine, used as the mountant, it lasts much longer than it does 

 in balsam. This is the first instance that has yet come under my 

 notice, since using paroleine as a mountant, in which it has failed 

 to preserve or retain an aniline dye. 



There are doubtless many microscopists who would follow 

 some branch of cytological research, were there not an almost 

 general impression that such work requires much skill and delicate 

 manipulation, which deters them from taking up the work. 



Surely all branches of microscopical technique, manipulation, 

 etc., and the interpretations to be drawn from the same, must of 

 necessity require due care and skill, but certainly cytology makes 

 no demands that should deter many who would like to enter this 

 field from so doing, and I trust that the above description of my 

 method is lucid enough to stimulate would-be workers to action, 

 not to repel them. 



Although many points regarding microscopical technique and 

 manipulation are somewhat difficult of explanation in a written 



