The Staining of living Nuclei. 573 



nuclei which had in the meantime moved further apart, and a little later 

 the cell-plate was evident as a distinct line in the sanie place. The 

 nuclei became more and more rounded and this was accompanied by a 

 more uniform distribution of the chromatin, the segments appearing to se- 

 parate gradually into separate microsomes. In an hour and a half from the 

 beginning of the Observation the division-wall was formed entirely across 

 the cell, but the nuclei were still slightly flattened. Two hours later the 

 same cell was examined and the division was found to be complete, the 

 nuclei having assumed the form and size of the ordinary resting ones. 

 Owing to the Separation of the microsomes the nuclei were noticeably paler 

 in color than when first seen. 



A fine nuclear stain was also observed in this species in the paren- 

 chyma of the stem. The best results were had by staining directly on the 

 slide. Rather thin longitudinal sections are made and mounted in water. 

 Gare of course must be taken to have the razor as sharp as possible so as to 

 injure the cells as little as possible. A drop of -1 ^ dahlia or mauvein 

 Solution is then run under the cover glass and allowed to remain for about 

 10 minutes, the section can be watched under the microscope and the color 

 regulated accordingly. The stain thus obtained is very marked and the 

 Streaming of the protoplasm only slightly checked. The Streaming is usu- 

 ally to be seen in the protoplasmic threads running from the nucleus, or in 

 the thin layer lining the walls. 



Owing to the ease of preparation as well as to the large size and dis- 

 tinct outline of the nucleus, this is one of the very best objects for the de- 

 monstration of nuclear staining, The sections should be made from a rather 

 young stem as in the older ones the accumulation of starch is somewhat 

 troublesome. 



Tradescantia rosea. 



With this species which closely resembles T. Virginica, similar results 

 were obtained so far as very limited observations went, and probably it 

 would prove an equally good subject. 



Tradescantia eil lata. (?) 



The species grown under this name in the Tübingen botanical garden 

 is also in habit similar to T. Virginica, but the flowers are much smaller. It 

 blooms later than that species and for this reason was used after the flower- 

 ing time of the other was over. Owing to the smaller size of the buds it 

 is less convenient to handle but still answers very well. 



With this species numerous experiments were made with dahlia and 

 mauvein, and a few with methyl-violet; the deepest color was obtained 

 with mauvein, which seemed on the whole to give better results with this 

 species than dahlia. 



