The Microscope. 211 



all pink. Then wash in two alcohols of 95 per cent., drop into 

 clove oil for a few moments only, and mount in Canada balsam. 

 They are thus very instructive. — V., A. Latham in Scientific 

 Inquirer. 



Coloring the Nuclei of Living Cells. — The most interesting 

 fact brought out in Mr. D. H. Campbell's work at Tubingen is the 

 fact that several anilin colors have the property of coloring the 

 nucleus of many plant cells without killing them. That the living 

 nucleus can be stained has been demonstrated by several observers 

 in the case of animal cells, but, so far as he knows, it has not 

 hitherto been observed in plant cells. Though the work is not yet 

 completed, he thinks it will be interesting to give briefly some of 

 the processes by whicli the results were obtained, and some of the 

 objects employed. 



The first color used was dahlia, a violet-purple pigment, by 

 whose aid Lavalette had succeeded in coloring living spermatozoa 

 and the nuclei of sperm- cells. The most favorable object so far 

 found by the author is nucleus of the cells of stamen hairs of Trx- 

 descautia. T. Virginica was principally used, but other species gave 

 equally good results. Hairs should be chosen from young buds, as 

 these are perfectly colorless, not having developed the colored cell-sap 

 of the older hairs. The sepels and petals are removed, and the 

 stamens thus exposed are plunged into an aqueous solution of the 

 dahlia. After an immersion of from half an hour to three or four 

 hours, or even much longer, depending on the strength of the solution, 

 it will be found that in many cases the nuclei are more or less 

 deeply colored, and that the cell is not killed is evinced by the 

 continuance of the protoplasmic streaming. It is quite surprising 

 to see how deep the nucleus is often stained without killing the cell. 

 A nucleus so colored appears perfectly normal, there being no dis- 

 tortion or change beyond the change in color. As yet he has not 

 studied especially what parts of the nucleus are colored, but it 

 appears to be the nucleolus and microsomes only, as in the case of 

 cells that have first been killed and then stained according- to the 

 ordinary methods. 



Among other objects that have given more or less satisfactory 

 results were the hairs from the base of the perianth of Lilium bulbi- 

 ferum, stamen hairs of Aphodelus albus, leaves of Elodea Cana- 

 densis and Vallismeria sprialis. root hairs of Trianca Bogatensis, 

 Cucurbita Pipo, Tradescantia zebrina, spermatozoids of Chara, 

 and a fern (probably Blechnum). In all cases cells were chosen in 



