February, 1920] PHYSIOLOGY 65 



the day on bright days. This difference is ascribed to the xerophytie environment under 

 which the wild oat normally prows. The moisture, soil and light requirements and the sto- 

 matal behavior of the cultivated species studied were essentially the same, though not iden- 

 tical. The authors call attention to the fact that light, the factor which regulates the rate of 

 food manufacture, also regulates the opening of the stomata through which raw material for 

 food manufacture enters. — E. W. Sinnott. 



MINERAL NUTRIENTS 



437. Skinner, J. J., and F. R. Reid. The influence of phosphates on the action of alpha- 

 crotonic acid on plants. Amer. Jour. Bot. 6: 167-180. Fig. 1-9. 1919. — Alpha-crotonic acid, 

 even in low concentrations, is harmful to plants. The action of nutrient salts in counter- 

 acting this effect was studied. Wheat plants were grown in a nutrient solution of calcium 

 acid phosphate, sodium nitrate and potassium sulphate, one set with and another without 

 cro tonic acid. The familiar "triangle" system was used to study the effect of various pro- 

 portions of nitrate, phosphate, and potash. The green weight of plants produced after 12 

 days was determined. Crotonic acid was found to depress this weight on the average of 52 

 per cent, but to have a much less harmful effect in solutions high in phosphate than elsewhere. 

 To determine whether the calcium or the phosphate or both were important in causing this 

 effect, sodium salts were substituted for calcium. Mono-, di- and tri-sodium phosphates, 

 respectively, were used, the other members of the solutions remaining unchanged. Mono- 

 sodium phosphate was similar in its effects to mono-calcium phosphate. Di- and tri-sodium 

 phosphates, however (which are alkaline rather than acid in reaction), when in relatively 

 strong concentration, counteract even more markedly the harmful effect of the crotonic 

 acid. The effect of crotonic acid is therefore much ameliorated by the presence of phosphate 

 and is less severe in solutions containing alkaline salts. — E. W. Sinnott. 



, METABOLISM (GENERAL) 



438. Bourqtjelot, Em., and H. H^rissey. Application de la methode biochemique a 

 l'etude des feuilles d'Hakea laurina. Extraction d'un glucoside (arbutin) et de quebrachite. 

 [Biochemical methods applied to the study of the leaves of Hakea laurina. Extraction of arbu- 

 tin and quebrachite.] Compt. Rend. Acad. Sci. Paris 168:414-417. 1919. [See Bot. Absts. 

 3, Entry 426.] 



439. Combes, Raoul. Recherches biochemiques experimentales sur le role physiologique 

 de glucosides chez les vegetaux. [Biochemical investigations on the physiological role of glu- 

 cosides in plants.] Rev. Gen. Bot. 29: 321-350, 353-376. PI. 1-3. 1917. Ibid. 30: 5-16, 33- 

 50, 70-93, 105-106, 146-157, 177-205, 226-238, 245-270, 283-301, 321-322, 355-364. PL 14, 15, 

 16, 18. 1918.— This paper, which gives the facts gained during a period of nearly ten years of 

 experimental work, contains a review of the general history of glucosides; a discussion of some 

 new external and internal factors that determine the glucoside content of the plant; with a 

 detailed account of new apparatus, its use, and the results of experiments. The plants were 

 grown under sterile conditions throughout the period of experimentation, by the strict ster- 

 ilization of seeds, media, and all apparatus. Small plants were cultivated in special tubes so 

 that the gas they used was sterile, being allowed to circulate through cotton stoppers. Knop's 

 medium with and without the addition of a specific glucoside was used as the principal culture 

 medium. These nutrient media were made solid when necessary by the addition of 5 per cent 

 gelatine or pumice. At the end of the culture period the sterility of the medium was tested 

 by bouillon inoculation. This was followed by a quantitative analysis of the medium, the plant 

 stem, and the plant root, which gave data on the absorption and excretion of material. Plants 

 grown under sterile conditions such that their roots were in contact with a nutrient medium 

 containing a specific glucoside behaved according to the species to which they belonged. 

 Thus Agrostemma Githago grew in solutions containing from 1 to 10 per cent of agrostemma 

 saponin (extracted from Agrostemma seeds) without showing any signs of suffering, while 

 plants not related to this species (Polygonum and Rapkanus) grew only in to 0.1 per cent 



