Botanical

rsion lenses, one may apply a heated metal wire to the edge of the cover-glass, as Vosseler (II, 297) has done. The same object may also be attained, according to Pfeiffer (I), by encircling the cover with Canada balsam. Various stained tissues, especially carmine, ha?matoxylin, and saffranin preparations, may be excellently preserved in Venetian turpentine, according to Vosseler. In my own experience, however, acid fuchsin seems to be more poorly preserved in it than in Canada balsam. VI. Staining of Living Tissues. 28. As has been shown especially by the researches of Pfeffer (II), it is possible in very many cases to cause living plants and parts of plants to take up certain coloring matters. This so-called live staining is not only of great importance for the study of the transportation of material within the vegetable organism, but has also led to some interesting results concerning the morphology of the cell, and should certainly be capable of still wider application. For the success of live staining it is of primary importance that the staining solution used should exercise no injurious effect upon the objects concerned. Since the aniline colors generally act as poisons on plant-cells, it is necessary to use them in very dilute condition, when they affect the cell very little or, in general, not injuriously. An evident staining can, it is clear, only take place when the stain is stored up by certain constituents of the cell. This is generally the c...