1 889.] BOTANICAL GAZETTE. 



I 99 



BKIEFER ARTICLES. 



Studies in nuclear division.— It may not be generally known that 

 nuclear division, in certain cases at least, may be easily and quickly stud- 

 ied, and a few hints here may not be out of place. 



The readiest means of studying this interesting subject is probably 



to be found in the final divisions of the pollen mother-cells, especially of 



monocotyledons. I examined a number of plants recently, and among 



them found two in particular that showed very beautifully all of the 



stages in the division of the nucleus, including the longitudinal division 



of the nuclear segments 1 , and were thoroughly typical representatives of 



the differences in the processes as found in monocotyledons and dicoty- 

 ledons. 



The first of these was Allium Canadense, the second Podophyllum 

 peltatum. 



Young buds must be used, in Allium about 2mm. in length; in Pod- 

 ophyllum buds were gathered as soon as the plants appeared above 

 ground. In the former case the young anthers were crushed carefully 

 in a drop of acetic acid and w ? ater (£ acetic acid and £ distilled water). 

 With Podophyllum cross-sections of the whole bud were made, and the 

 sections of the anthers teased out in the same solution as in the case of 

 Allium. The pollen mother-cells are at once recognizable by their thick 

 colorless walls, and it is easy to tell with a low power whether or not the 

 desired division stages are present. If this is the case they may be 

 stained with acetic methyl-green, or better, gentian-violet. In preparing 

 the latter the best results were had by first mixing two parts of distilled 

 water and one of acetic acid. To this mixture a sufficient quantity of 

 a saturated alcoholic solution of gentian-violet was added to give it a 

 deep violet color. If a small drop of this mixture is now added to the 

 preparation containing the pollen cells, the nuclei will be almost instantly 

 colored a deep blue-purple, while the protoplasm remains colorless and 

 entirely uncontracted. The coloring fluid may now be carefully re- 

 moved with blotting-paper, care being taken, of course, to avoid remov- 

 ing any more of the floating pollen mother-cells than is necessary, and 

 the preparation mounted in dilute glycerine, which must be added very 

 gradually to avoid contraction of the protoplasm. Specimens prepared 

 in this way, especially when first made, show all the finest details of the 

 nuclear structure, and scarcely, if at all, inferior to those prepared by the 

 much more tedious and uncertain methods of fixing by alcohol, chromic 

 or picric acid, etc., staining with hsematoxylon, carmine or safranin, and 

 mounting in balsam.— Douglas H. Campbeli* Blooming ton, Ind. 



x The author expects later to publish a more extended account, with figures, of these 

 two plants, with possibly some additional matter bearing on the subject 



