Neutral Violet Research Articles

A contribution to the colloidchemical and morphological study of chromosomes

1. Chromosomes in the pollen mother cells ofTradescantia virginica generally can not be distinctly observed in a cane sugar solution of a certain concentration, the part of the cell occupied by the chromosomes looking even transparent. This apparent disappearence of the chromosomes is a result of overswelling of their gelatinous substance due to the [H.] of the medium. The less acidic the medium is, the more the chromosomes swell up. 2. This phenomenon can be explained from the view point of the physico-chemical nature of the nucleic acid, regarding it as a fundamental constituent part of the chromosome. 3. It is a necessary precaution to consider the [H.] and the buffer action of the medium, when the chromosomes are observed directly in the fresh state. 4. The colloidal state of the chromosomes displayed in the 0·025% solution of the neutral violet extra and the spiral structure seen in them, can not be regarded as a result of coagulation. It seems rather to be very near the natural structure.

Das botanische Practicum

THE third edition of this well-known book has been so favourably received that a fourth edition has now been published. The alterations and additions in this new issue are not so extensive as in the previous one, but they are nevertheless considerable, and the whole book has been subjected to careful revision. The scope of the book has certainly advanced beyond the author's original intention as conveyed by the title, “Introduction to the Personal Study of Microscopic Botany,” for there are references to several important facts which are highly interesting, but the experiments connected with them one would not think of undertaking unless they formed part of an original investigation; parthenogenesis in Marsilia and the problem of intramortal or intravital staining are notable instances. As the facts are stated without critical opinions being offered, a simple reference to the publications would have been as valuable, and would have made a reduction even though slight in the size of the book. However, the greater number of the additional paragraphs are of considerable practical value, and not the least so are the directions or hints which emanate from Prof. Strasburger himself or from workers in his laboratory, as, for instance, the method of examining the root of Vicia Faba, the directions for embedding small algae and the instructions for demonstrating protoplasmic threads (Plasmodesmen). Other notable additions include new tests for starch, fats, callus and cork, and the use of neutral violet as a reagent for pectic compounds. Darwin's device of using hornshavings as a hygrometer to determine the number of stomata and Buscalioni's collodion method for the same purpose are mentioned, and some account is given of Brown and Escombe's work on the diffusion of gases through small apertures. It will be found that this edition differs mainly by the insertion of new paragraphs, and practically the only chapter which is rewritten is the last, dealing principally with cell problems.