244 THE CYCLE OF CELL-DIVISION 



which have been induced in cells, mitosis should not 

 be described as the phenomenon of nuclear division. 

 It is part of the cycle of cell-division, and the whole 

 of the cell-protoplasm takes part in it. The Altmann 's 

 granules form the chromosomes, the nucleolus forms 

 the centrosomes, and the nucleus forms the spindle. 

 The protoplasm of the cytoplasm and cell-wall also 

 reproduces itself and divides during mitosis. 



The active principle in the stain which causes 

 mitosis in lymphocytes is a constituent of the azur 

 dye. This dye also contains a substance which kills 

 the protoplasm, and having done this it will, if in 

 sufficient concentration, cause that protoplasm to stain 

 scarlet. Mitosis occurs by the action of the active 

 principle on the chromosome granules; cell death 

 occurs by the action of the poison on the centrosomes. 

 So far the active principle has proved to be inseparable 

 from the poison in the anilin dye. 



Up to this stage in the researches the only sub- 

 stance we had found which would induce divisions in 

 lymphocytes was this anilin dye; but its action was 

 augmented by atropine and an extract of dead haemal 

 gland. Atropine augments its action five-fold if it is 

 absorbed in suitable strength, in which case it may 

 induce asymmetrical mitosis. Neither atropine, in no 

 matter what strength, nor extract of dead haemal gland 

 in the strength of 100 per cent will by themselves 

 induce mitotic figures in lymphocytes. 



Great care must be exercised in the practice of 

 inducing the mitotic figures in lymphocytes. The 

 jelly must be accurately prepared, but it is better to 



