SPECIAL METHODS 153 



that such sohitions never stain the nucleus, and that if the nucleus 

 stains at all, it is an indication that death is taking place. 



Campbell succeeded in staining the living nuclei in the stamen hairs 

 of Tradescantia by using dilute solutions of dahlia and of methyl violet 

 (0.001-0.002 per cent in water). Dividing nuclei were stained. 



For determining the stage of development of fresh material it is 

 often necessary to use a stain. For this purpose stronger stains may 

 be used, since it is unimportant whether the tissue is killed or not. An 

 aqueous solution of methyl green or eosin can be recommended. With 

 1 per cent solutions, diluted one-half with water, mitotic figures can be 

 recognized with ease. 



