728 EXPERIMENT STATION EECOED. 



such isolated events; and that the change which we see as a nascent variation 

 is often, perhaps always, one of loss." 



The second part of the paper is devoted to the development of his conclusions 

 in regard to man. 



Physiological plant anatomy, G. Haberlandt, trans, by M. Drummond 

 (London, 191Jf, pp. ZF+777, figs. 291).— This work is a translation of the 

 fourth German edition which appeared in 1909. and is considered as represent- 

 ing the mature views of the author. The scope of the work may be shown by 

 the definition given to physiological plant anatomy: "It consists first, in the 

 recognition of the physiological functions pertaining to the tissues of the plant 

 and to the structural units, or cells, of which these tissues are composed ; and 

 secondly, in the discovery of the connection that exists between the several 

 functions and the anatomical arrangements required for their proper per- 

 formance." 



Chapters are given on the cells and tissues of plants, meristematic tissues, 

 and dermal, mechanical, absorbing, photosynthetic, vascular or conducting, 

 storage, aerating or ventilating, secretory and excretory, motor, sensory, and 

 stimulus transmitting systems. A chapter is also given on the secondary growth 

 in thickness of stems and roots causing both the normal and anomalous forms. 



By means of copious notes additional data are given to support \arious state- 

 ments, and controverted points are discussed at some length. This book will 

 undoubtedly ))e a noteworthy addition to the available literature in the English 

 language relating to the general field of the physiology of plants. 



On chlorophyll and leaf pigments and those of flowers and berries, R. 

 WiLLSTATTER {'Saturwisscncliaftcn. 2 (1914), No. 19, pp. //6S-//T0).— This is a 

 brief note of a paper read before the German Chemical Society. 



It is stated that the composition of chlorophyll is largely independent of 

 season, time of day, and illumination, also that the composition of the par- 

 ticular pigments involved varies but slightly. The characteristic coloring 

 matter of the cornflower is thought to bo identical with that of the rose and 

 to have as a basis some potassium comi)Ound. 



Winter as a factor in the xerophily of certain evergreen ericads, F. C. 

 Gates {Bot. Gaz., 57 U9W, No. 6, pp. U^-489, figs, i^).— The author, giving 

 results of work carried on from 1910 to 1912, states that the transpiration 

 of all plants tested was very low in winter, often being imperceptible at 

 night. A gain of weight occurring at low temperatures indicated absorption, 

 in some cases sufficient to overbalance transpiration. Transpii-ation per unit 

 surface of evergreen shrubs was from 4 to 30 times that of deciduous shrubs 

 during cold winter weather, also under warm indoor conditions. 



In case of peat bog plants in nature, light, particularly sunlight, seems to 

 be the effective factor in causing stomatal movements. These appear to be 

 less influential in regelating transpiration of peat bog plants than the evaporat- 

 ing power of the air. 



Thermotropism in roots, H. D. Hooker, jr. [Plant World, 17 {19W, No. 5, 

 pp. 135-153). — Summarizing conclusions reached from details obtained in nine 

 experiments on thermotropism as carried out with .seedlings of Ervum. 

 Pisum, Phaseolus, I.upinus, and Zea sprouting in agar, the author states that 

 the use of a 1.25 per cent solution of agar as a medium for the roots effectu- 

 ally excludes all factors except the difference of temperature, but allows the 

 roots to grow and bend; that no thermotropic reactions occur when such 

 agar is used; that reactions occurring in such cases must be attributed to 

 positive hydrotropism; and that traumatropism enters as a factor at higher 

 temperatures. 



