292 PHYSIOLOGY [Bot. Absts., Vol. V, 



2236. Pulling, Howard E. Sunlight and its measurement. Plant World 22: 151-171, 

 187-209. 5 fig. 1919. — The author presents a general discussion of the nature, distribution, 

 and variability in amount of solar radiation reaching the earth, as modified by extra-terrestrial 

 influences, and by atmospheric conditions. Three general methods of measuring radiation 

 are discussed: radiometry, photometry, and actinometry. The difficulties involved in each 

 method, their limitations, the precautions to be observed in manipulating the instruments, 

 and the interpretations of measurements are considered. An extensive bibliography accom- 

 panies the text. — Charles A. Shull. 



2237. Raunkiaer, C. Uber das biologische Normalspektrum. [The biological "normal 

 spectrum."] Kgl. Danske Vidensk. Selskab. Biol. Meddel. I 4 : 1-18. 1918. 



2238. Schanz, Fritz. The effects of light on plants. Sci. Amer. Monthly 1 : 12-16. 1920. 

 [Translated from the Biologisches Cenlralblall (Berlin).]— Some of the topics considered are: 

 how light affects the albumens of plants; substances which act as catalyzers; the meaning of 

 colors in flowers; and effect on plants of varying intensity of light. — Chas. H. Otis. 



TOXIC AGENTS 



2239. Breasola, M. Le devitalizzazione dei semi di Cuscuta. [The killing of Cuscuta 

 seeds.] Staz. Sperim. Agrarie Italiane 52: 193-207. 1919.— See Bot. Absts. 5, Entry 1112. 



2240. Ciamician, G., and C. Ravenna. Sul contegno di alcune sostanze organishe nei 

 vegetali. Nota XI. [On the behavior of certain organic substances in plants. Xlth contribu- 

 tion.] Gaz. Chim. Italiana 49: 83-126. PI. 1-2, fig. 1-20. 1919.— The present contribution 

 is divided in two parts. Part I. The authors study the effect on the growth of beans (germin- 

 ated in cotton and distilled water) of repeated doses of one per thousand solutions of the 

 substances investigated. In nearly every case when galvanized iron containers were used 

 instead of glass, there was a distinct reduction in toxicity of the compounds studied. The re- 

 sults may be summarized as follows: Mono-methyl-amine was slightly toxic while di-methyl- 

 amine and tri-methyl-amine were more toxic in the order named. Ammoniacal salts, urea, 

 pyridine and uric acid show no toxic action in the conditions studied while tetra-methyl- 

 ammonium tartrate and tetra-ethyl-ammonium tartrate, piperidine, nicotine, and theobro- 

 mine are very slightly, if at all, toxic. The function of the methyl group in toxicity is brought 

 out very plainly by the fact that potassium salicylate is very slightly toxic while methyl 

 salicylate is distinctly toxic. A list is given of the substances found to be toxic under the 

 conditions mentioned. Part II. This section is given to the study of the oxidative changes 

 undergone by some organic compounds when incubated with spinach pulp in the presence 

 of adequate oxygen and of small amounts of toluol as an antiseptic. Attention is also given 

 to the inoculation of some compounds into living maize and to the changes undergone by these 

 in the living organism. Two examples will indicate the direction of the results. Succinic 

 acid, which by the action of light is transformed to acetic aldehyde, acetic and propionic 

 acids, also glyoxal, is changed by plant enzymes into acetic aldehyde and a compound de- 

 composed by emulsion. Lactic acid in the light yields acetic acid and acetic aldehyde, while 

 only the latter compound results when acted upon by enzymes. In respect to the above the 

 general conclusions is that the enzymes of spinach leaves have a selective oxidizing function 

 which in some cases does not equal the action of light, though surpassing it in other cases. 

 With respect to the behavior of organic compounds inoculated into maize and tobacco the 

 results obtained point to the fact that compounds very resistant to oxidation, such as pyri- 

 dine and benzoic acid, are only found in very small amounts in the extract of the plats after 

 inoculation. The strong oxidizing power of plants and especially of living plants may not be 

 due to the ordinary oxydases, but more probably to protoplasmic enzymes insoluble in water 

 and apparently also in glycerin.— A. Bonazzi. 



2241. Malisoff, William, and Gustav Egloff. Ethylene. Jour. Phys. Chem. 23: 

 65-138. 1919. — This is a collection ' 'on a logically convenient basis' ' of the physical and chem- 

 ical data on ethylene, including references to its effects on plants. A bibliography of 324 

 citations is appended. — //. E. Pulling. 



