1920] AGRICULTURAL BOTANY. 819 



considered important contributions to ttie methods employed In phylogenetic 

 .study in plants. 



Studies in electrophysiology, A. E. Baines (London: George Routledge d 

 Sons, Ltd., WIS, pp. XXIX+2yi, pin. 10, figs. 161).— The author gives an ac- 

 count of studies on animal and vegetable electrophysiology conducted by him- 

 selt during some years. The principal conclusion arrived at is that everything 

 living possesses a well-delined electrical system, while the nonliving has capacity 

 only. 



Every tree, shrub, fruit, vegetable, tuber, and seed is an electrical cell that 

 c;kn not be polarized or discharged so long as it remains structurally perfect. 

 The skin, peel, rind, or jacket of fruits and vegetables is a sort of insulating 

 substance designed primarilj' for the conservation of electrical energy. The 

 electromotive force is the same in all, the current varying in accordance with 

 Ohm's law. 



Plants grown in pots or removed from the earth and placed in other recep- 

 tacles differ materially in their electrical constitution from those grown in the 

 earth. If a suitable electrolyte, other than water, is mixed with the soil it is 

 possible to grow plants with much less moisture. Growth may be stimulated by 

 means of a continuous current of electricity of low potential and proper sign. 



Broadly speaking, the edible part of a fruit or vegetable is the positive ele- 

 ment, or that part which yields a positive galvanometric reaction. Dry earth 

 is a bad conductor of electricity, and therefore water is required as an elec- 

 trolyte, being necessary also in the formation of protoplasm. 



Physiological studies on tree architectonics, H. Lundegakdh {K. Svensku 

 Vdeiisk. Akad. Handl.. 56 {1916), No. 3, pp. 6Jf, pis. 11, figs. i7).— These studies 

 deal with tree form, structure, and modifications of these during growth under 

 various influences. 



Recent studies on growth in thickness of trees, P. .Taccard {Nouvelles 

 Rccherches sur VAccroissenient en Epaisseur des Arbres. Zurich: Fondation 

 Schnyder von Wartensee, 1919, pp. XII +200, pis. 32. figs. 74). — These studies 

 were intended to test the author's physiological theory of tree growth. They are 

 divided into five main parts dealing respectively with the tree stem as offering 

 equal resistance to flexion ; the trunk considered as having equal conducting ca- 

 pacity for water; mechanical actions resulting from growth in thickness (also 

 influence of weight and geotropism ; experiments carried out with trees of 

 numerous varieties; and considerations bearing upon a physiological theory of 

 growth, concentric and eccentric. 



Summing up a large number of detailed conclusions, the author holds that the 

 general form of trees is not the product of a gradual selection of useful varia- 

 tions, but that it is determined principally by the factors, both mechanical and 

 physiological, which act in analogous ways in all of the arborescent species. 



Heat production and temperature in living plants, E. Leick (Biol. Zentbl.. 

 S6 (1916). Nn. 6-7. pp. 2.'fl-261). — This is mainly a bibliographic discussion of 

 biological production of heat, respiration being regarded as the most importan; 

 source in plants as well as in animals. 



The influence of light on the fructification of Agaricacear in pure cul- 

 ture, R. Matre and M. de Laroquette (Bui. Soc. Hist. Nat. Afrique Nord, 10 

 (1919), No. 5, pp. 94-106, pi. 1). — The authors name 35 genen of Autobasidi> 

 niycetes with about twice as many species, from cultures of which variojs 

 authors named have obtained fructification. The results fu'e given of tests on 

 the influence of factors (principally illumination) on fnctification. 



Length of day instead of temperature controls t*^e of flowei-iug ans) 

 fruiting (Torrrjia. 20 (1920). No. 3. pp. 46-50).— This i- a conden.sed acoounr «( 

 the work and conclusions reported by Garner and Ali^^d (E. S. R., 42, p. 818). 



