2668 Journal of Applied Microscopy 



tern rotates on the lower, so that two pictures may be thrown at the same time 

 upon screens placed side by side. We have a curtain for use with the upper 

 lantern, but the screen just described is so much more satisfactory that we use it 

 altogether, except where both are needed at once. 



The frame for the screen must be well braced, to guard against warping, for 

 the cardboard absorbs so much moisture from the kalsomine that it exerts a 

 good deal of a pull on the frame. Evidently, also, the larger the sheets of card- 

 board the fewer will be the joints and the smoother the surface. The sheets we 

 used were bought originally for chart making and were about 2^^ by 3i^ feet. 

 This made an excessive number of joints, but the kalsomine covers them so well 

 that they are not noticeable when in use. Aaron L. Treadwell. 



Vassar College. 



Mitosis in Root-tip of Hyacinthus. 



The several species of the cultivated Hyacinth ofifer very good material for 

 the study of indirect nuclear division, in that their roots are mostly large and 

 grow rapidly. Water cultures grown in a hothouse are especially to be recom- 

 mended, and the young roots are to be cut off close to their point of emergence 

 from the root-bearing area of the bulb, when they have attained a length of about 

 one-quarter inch, as they are then in a most active stage of growth. A good 

 plan also is to allow roots to grow for some time and then to cut off all except a 

 few that are just coming through ; these latter then grow very rapidly and are 

 eminently suited for the preparations required for the study of mitosis. 



For this purpose, the roots are hardened and fixed in Flemming's solution 

 (I have found the following strength very suitable for hyacinthus: osmic acid .1 

 per cent., chromic acid .1 per cent., glacial acetic acid .2 per cent.). The roots 

 remain in this for a day and are then washed in distilled water and subsequently 

 transferred to pure spirit (methylated). From this material it is easy to cut 

 very thin longitudinal sections, about one cell thick, by hand, the root being fixed 

 in split pith. This method is certainly quite as good as paraffin embedding and 

 does not disorganize the cells so much. 



For staining, I can recommend single-staining, either with acetic methyl- 

 green or concentrated aqueous solution of gentian-violet (Griibler's). Double 

 and triple staining gives good results, but if safranin is used, it should be in 

 dilute aqueous solution and the sections should not be allowed to remain in it 

 for more than 5 minutes. Before staining at all it is advisable to treat sections 

 with 5 per cent, solution of hydrochloric acid, in order to dissolve out the saphides 

 which exist in certain cells of the section ; then wash them. With these pre- 

 cautions very good results may be obtained, the sections being mounted as usual 

 in xylol-balsam. All stages in mitosis may be found in a section, and the pre- 

 paratory stages are particularly fine as also are monastes figures. The disastes 

 phases are not quite so clear, owing to the large number and closeness of the 

 separate loops, but in some cases distinct loops can be made out and counted. 



The formation of the cell-plate is very clear and the separate thickenings on 

 the spindle-fibrils are quite distinct. I could not find centrosomes, but this is 

 probably on account of inadequate staining processes ; if present, they are ex- 

 ceedingly small, although the nuclei are relatively enormous when compared 

 with those of other plants, even Fritillaria. I may mention that, amongst the 

 Liliaceae, Hyacinthus and Fritillaria are perhaps the two best for the study of 

 mitosis. Harry A. Haio. 



London, England. 



