No. 1, February, 1921] PHYSIOLOGY 61 



conditions resulting in a high transpiration rate more alkaline solutions give better results. 

 "Wheat, corn, and peas are sensitive in the order named to high hydrogen ion concentra- 

 tion." — "Usually the addition to Solution B of small amounts of dibasic potassium phosphate, 

 of solid calcium carbonate, and of aluminum hydroxide has given increased yields, often 

 considerably above that of the unmodified solution." — The results indicate in general that 

 there is no "best" solution for the growth of any of the plants used for this work. When the 

 "Ph of the solution is considerably less than neutrality there is generally a tendency for this 

 to be shifted toward the neutral point," depending upon the composition of the solution and 

 upon the plant. — S. M. Zeller. 



403. Greaves, J. E. The antagonistic action of calcium and iron salts toward other salts 

 as measured by ammonification and nitrification. Soil Sci. 10: 77-102. 20 fig. 1920.— See 

 Bot. Absts. 7, Entry 451. 



404. JoHxsTo.x, Earl S. Nutrient requirement of the potato plant. Plant World 22: 

 329-336. 4 fig- 1919. — Difficulty was experienced in securing uniform potato plants for the 

 experiments. Cuttings from potato vines, and sprouts removed from tubers at an early 

 stage of development were not satisfactory. Somewhat older sprouts which had well devel- 

 oped roots at time of separation were used. The nutrient solutions employed were made 

 up to one atmosphere osmotic pressure with monobasic potassium phosphate, calcium nitrate, 

 and magnesium sulphate. Roots showed a tendency to rot in the culture solution. The 

 best growth was obtained in a three-salt solution in which the larger amount of the osmotic 

 pressure was due to calcium nitrate. — Chan. A. Shull. 



405. MoLLiARD, M. Influence d'une dose reduite de potassium sur les caracteres physio- 

 logiques du Sterigmatocystis nigra. [The influence of an insufficient supply of potassium on 

 the physiological characteristics of Sterigmatocystis nigra.] Compt. Rend. Acad. Sci. Paris 

 170:949-951. 1920. — This is a comparison of cultures of Sterigmatocystis nigra containing 

 potassium in an amount which insures optimum development and those which have the 

 amount reduced. Full nutrient solutions contained 0.95 g. of KH2PO4 to 1000 cc. of water, 

 the potassium-low solution contained 0.0119 g. It is found that in potassium-starved cul- 

 ture the increase in dry weight is much slower; the sugar consumed in 20 days is equal to that 

 consumed in full nutrient solution in two and two-thirds days. The sugar consumed instead 

 of giving rise to CO2 gives rise to oxalic apid. There is an absence of conidia and black 

 pigment and the rapid formation of a yellow pigment. A liquid is also produced which is 

 soluble in the solutions and stains blue with iodine. — C. H. Farr. 



406. Parker, F. W., and E. Truog. The relation between the calcium and the nitrogen 

 content of plants and the function of calcium. Soil Sci. 10: 49-56. 1 fi^. 1920. — A tabulation 

 of data on the ash content and nitrogen content of crop plants shows a close correlation 

 between the calcium content and nitrogen content. Potassium, phosphorus, and magnesium 

 show no such relation. The important agricultural plants can be divided into those having a 

 low calcium-nitrogen ratio and low lime requirement, and those having a high calcium- 

 nitrogen ratio and a higher lime requirement. The calcium neutralizes the plant acids 

 formed in protein metabolism. — W . J . Rohhins. 



METABOLISM (GENERAL) 



407. Allen, E. R. On carbohydrate consumption by Azotobacter chroococcum. Ann. 

 Missouri Bot. Gard. 7: 75-79. 1 fig. 1920. — With a knowledge of some of the defects of pres- 

 ent experimental methods for the study of the physiology of Azotohacter, three improve- 

 ments are suggested for cultures. They are (1) renewal of the energy source in order to in- 

 crease growth and to produce more marked changes in the amounts of metabolic products; 

 "(2) simultaneous determination of nitrogen and of residual carbohydrates at short inter- 

 vals" so as to obtain "a more complete picture of the growth processes of Azotohacter f and 

 (3) "operations to facilitate experimental manipulation and possibly obtain even better 



