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CURRENT LITERATURE. H5 Stiles, W., and Kidd, F. The influence of external concentration on the position of the equilibrium attained in the intake of salts by plant ceils. Pro. Roy. Soc. B. 90 No. B. 632, p. 448 ivith graphs.

The authors have been conducting experiments with slices of living tissues to ascertain the position of equilibrium attained in the intake of individual salts, and allied phenomena. The method adopted is that of placing a certain number of washed thin slices of potato or carrot in different solutions the change in the electrical conductivity of which is taken as a direct measure of absorption, due regard being paid to the exosmosis which may take place at the same time. Kcl, NaCl or Cacl 2 solutions are normally absorbed, the rate of initial absorption increasing with the con- centrations of the solutions employed. Cu So t solution however causes exosmosis in excess of absorption, and thus seems to destory in a way the semipermeability of the cell. This phenomenon is more pronounced if stronger solutions -of Cu So ( are employed. Anomalous phenomena in the case of Alcl ;t are hoped to be explained in subsequent articles. The authors have not investigated the mechanism of the cell concerned.

Previous work on the subject conducted by Stiles W., and Jorgensen I., and published in Ann. Bot. Vol. XXIX a'id XXXI, supports the view that the method employed is a correct one. In these papers they discussed Czapek's theory of plasma membrane. It may be remembered that Czapek in 1914, started a theory that the mechanism concerned in the passage of salts is the outermost layer of protoplasm, containing lipoid matter. With reference to this theory they say that his experiments were crude and unscientific and his data wrong, that the rate of exosmosis is not a function of surface tension, and that there is ' not a shred of evidence ' in support of some of his assumptions such as the one tbat since "solutions whose surface tension with air is 0-68 are just strong enough to produce exosmosis from the cell therefore the surface tension of the outermost layer of protoplasm towards air must aho be 0-58". So they seriously doubt the verity of his simple theory of plasmolytic membrane as the mechanism in the intake of salts.

Therefore the phenomenon of the absorption of salts seems to be more complex than is usually supposed. It is not a case of mere diffusion.

M. Balasubrahmanyam.

Hole, R. s. Plant Diseases. Indian Forester Vol. XLV (1919) 584, Hole is of opinion that of recent years there has been a decided tendency to exaggerate the importance of fungi and to regard them as being the primary cause of most plant diseases. He feels that " if we are to make real progress in controlling the diseases of our forest plants, we must develop and expand the study of cecology, or as it is sometimes termed field physiology, and must regard plant diseases as ooraplex problems frequently requiring for their complete solution the oorabined efforts of a number of experts, such as oecologists, mycologists and biological chemists." A letter written by the iate Mr. Ch. Ogilvie Farquharson and reproduced from the Kew Bulletin, 1918, p. 353, expresses similar views. I quite agree with the opinion substantiatad by good reasons, but I should be sorry if the authorities of the Forest Department were to show less interest in the work done by their mycologists.

E. B.

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