AGRICULTURAL BOTANY. 131 



insight into tlie action of ultraviolet light on living cells, it was considered 

 necessary to study its effect on certain constituents of protoplasm, and atten- 

 tion was first given to the proteids. A series of experiments were made at the 

 laboratory of plant physiology at Harvard University with egg white, egg 

 albumin, and ox serum placed in quartz tubes and exposed at room temperature 

 to the light of a quartz mercury vapor lamp. 



The coagulum produced by the light in egg white and egg albumin was 

 insoluble iu alcohol, hot or cold water, and dilute acids, but was soluble in 

 dilute alkalis. In these respects it agrees with the ordinary coagulum pro- 

 duced by heat without exposure to ultraviolet light. 



The temperature coefficient of the coag-ulation caused by ultraviolet light, 

 W. T. BoviE (Science, n. ser., 37 (1913), No. 9J,9, pp. 373-375).— lu a previous 

 paper (see above) the coagulation of proteids when exposed to ultraviolet light 

 was shown, and the author has carried on experimauts to determine the nature 

 of the reaction, jjarticularly its temperature coefficient. Crystallized egg albu- 

 min in quartz test tubes was exposed to the light of a quartz mercury vapor 

 lamp and the coagulation estimated by measuring the amount of deposit in 

 the test tubes after centrifuging. 



When the tubes were kept at 0° C. they remained clear after having been 

 exposed to the light for 35 hours, while those exposed at a higher temperature 

 contained coagulum. When the tubes which had been exposed at 0° were 

 warmed their contents began to coagulate, and it was apparent that at least 

 two reactions took place, first, the change produced by light, and, second, the 

 production of a visible coagulum. It appeared that the action of the light 

 was about the same at the different temperatures, but that the substance at 0° 

 was unable to produce any visible coagulation. 



This experiment is believed to offer an interpretation of the results of Black- 

 man and Matthaei (E. S. R., 17, p. 234) regarding the effect of temperature on 

 the process of photosynthesis. 



The principal results of the experiments are summarized, the author stating 

 that two reactions are involved in the coagulation of proteids by light, the 

 chemical change and the production of a visible coagulum. The light reaction 

 has a very low temperature coefficient, while the reaction producing the visible 

 coagulum has a much higher temperature coefficient. 



Forcing- plants with radium, H. Molisch (Sitzber. K. Akad. Wiss. [V^enna^, 

 Math. Naturw. Kl, 121 {1912), I, No. 3, pp. 121-130, pis. 2).— The substance of 

 this article has already been noted from another source (E. S. R., 28, p. 228). 



The influence of thorium X on sprouting plants, F. Kahn (Munchen. Med. 

 Wchnschr., GO {1913), No. 9, pp. .'i5I,, Ji5'>, figs. 6). — As a result of a study with 

 oats and cress, the author claims to have found thar, while the effects observed 

 may vary considerably with different experiments and different stages, ex- 

 posure to smaller quantities of thorium X appeared generally to favor, while 

 larger quantities retarded, the germination of seeds and the gi'owth of plants. 



Recovery from hail wounds on woody plants, E. Voces {Centhl. BaJct. 

 [etc.], 2. AM., 36 {1913), No. 19-25, pp. 532-567, figs, ii).— This is a detailed 

 study of the cicatrization of fruits, the formation of protective structures in 

 bark, the peculiarities of parenchyma and sclerenchyma in renewed cortex, the 

 effects upon woody and other structures, etc., as observed 6 mouths after 

 widespread hail injury to various cultivated plants in northwest Germany. 



Toxicity of smoke, L. J. Knight and W. Crocker {Ahs. in Science, n. ser., 

 37 {1913), No. 9.'i9, p. 380). — Attention is called to publications of Molisch 

 (E. S. R., 27, p. 830) which indicate the extreme toxicity of tobacco smoke to 

 various plants. This toxicity has been found not to be due to volatilized nicotin, 

 but is believed to be due to carbon monoxid. 



