266 PHYSIOLOGY [BoT. Absts., Vol. IX, 



urease, rennet, and catalase. Tests for the presence of amidase, tannase, proteases, also 

 esterases acting on olive oil emulsion, andtriacetin showed negative results. — Otis F. Curtis. 



1637. Weiss, Freeman, and R. B. Harvey. Catalase, hydrogen-ion concentration and 

 growth in the potato wart disease. [Abstract.] Phytopath. 11: 57-58. 1921. 



METABOLISM (RESPIRATION) 



1638. Anonymous. Gaseous exchanges between plant roots and the air. Sci. Amer. 

 Monthly 3: 217. 1921. — This is a brief report of the results of the experiments of M. Raoul 

 Cerighelli (seeBot. Absts. 8, Entry 652). — Chas. H. Otis. 



1639. Gtjstafson, F. G. Comparative studies on respiration. II. The efifect of hydrogen ion 

 concentration on the respiration of Penicillium chrysogenum. Jour. Gen. Physiol. 2: 617-626. 

 1920. — For the most part measurements were taken of the time necessary to produce a given 

 amount of CO2, though in a few cases oxygen absorption was measured. Considering respira- 

 tion in a neutral solution as normal, changes in concentration between Ph 4-8 had practically 

 no effect on the normal rate. Decreasing the Ph value to 2.65 caused a gradual rise followed 

 by a gradual return to normal, while at Ph 1.10-1.95 the preliminary rise of about 20 per cent 

 was followed by a fall to below normal within 60 minutes. Increasing the Ph value to 8.80 

 resulted in a decrease in respiration to 60 per cent of the normal. The decrease in respiration 

 due to aPn value of 1.95 or less was not reversible, while a similar decrease in rate which 

 occurred at 8.80 was reversible. — Otis F. Curtis. 



1640. Nicolas, M. G. Contribution a I'etude des relations qui existent, dans les feuilles, 

 entre la respiration et la presence de I'anthocyane. [Relations between respiration and the pres- 

 ence of anthocyan in leaves.] Rev. Gen. Bot. 31: 161-178. 1919. — The author cites some 

 literature, the evidence from which indicates that there is a relation, though not a direct one, 

 between the presence of oxygen and the occurrence of red, blue, and similar pigments found 

 in fruits and flowers. — Of 2 plants belonging to the same species, one of which is red and the 

 other green, the former possesses fewer chloroplasts, manufactures less carbohydrate, and so 

 exhibits a less intense gaseous exchange. There is apparently a greater fixation of oxygen 

 in the red leaves than in the green. Where acids accumulate, there is a decrease in respiratory 

 intensity. The acids are the result of the incomplete oxidation of sugar, and the red color 

 depends on the formation of these acids. This accounts for the apparent necessity of oxygen 

 in the production of the red color. — J. M. Brannon. 



ORGANISM AS A WHOLE 



1641. FuLMER, Ellis I., Victor E. Nelson, and F. F. Sherwood. The nutritional 

 requirements of yeast. II. The effect of the composition of the medium on the growth of yeast. 

 Jour. Amer. Chem. Soc. 43: 191-199. 1921. — The following is the medium which the authors 

 find best for the growth of yeast: 100 cc. of the medium contains 0.188 gr. of ammonium 

 chloride, 0.100 gm. of dipotassium phosphate, 0.040 gr. of precipitated calcium carbonate, 

 0.60 gr. of dextrin, and 10 gr. of cane sugar. The authors think it possible that such a colloidal 

 material as dextrin protects the yeast against poisonous substances. — /. M. Brannon. 



1642. Hopkins, E. F. Hydrogen-ion concentration of the soil and seedling infection by 

 Gibberella saubinetii. [Abstract.] Phytopath. 11: 36-37. 1921. 



GROWTH, DEVELOPMENT, REPRODUCTION 



1643. Hopkins, E. F. Growth and germination of Gibberella saubinetii at varying hydro- 

 gen-ion concentrations. [Abstract.] Phytopath. 11: 36. 1921. 



