No. 2, December, 1920] PHYSIOLOGY 201 



cation of osmotic concentration in the tissues he regards as open to serious objection.— The 

 hydrogen-ion concentration he finds to be consistently a little lower in tumorous tissue, 

 whether produced by B. tumefaciens or (in Bryophyllum leaves) by freezing, than in adjacent 

 healthy tissue. He suggests that in tin- frozen t issues t Ids may be due to precipitation of pro- 

 teins. The activity of catalase ami of oxidase is found to be considerably greater in tumorous 

 than in healthy tissue, due evidently to the decrease in hydrogen-ion concentration there. 

 The growth of intumescences in frozen spots on Bryophyllum leaves is apparently due to the 

 higher rate of metabolism at these points and the consequent accumulation there of substano a 

 from the surrounding normal tissue. The author suggests that the dominance of a growing 

 apex may be due not to a production within it of inhibiting substances but to the attraction 

 to, and accumulation therein, of growth stimulating substances from the surrounding area. — 

 E. W. Sinnott. 



1354. Loeb, J. The nature of the directive influence of gravity on the arrangement of 

 organs in regeneration. Jour. Gen. Physiol. 2: 373-386. 1920. — Continuing work previously 

 reported the author shows that there is a close correlation between the distribution of a red 

 pigment in leaves of Bryophyllum calycinum and the development of shoots and roots in the 

 notches of a leaf. In leaves suspended vertically and sidewise in a moist chamber, roots and 

 shoots develop chiefly on the lower side. It is in this region also that the red pigment col- 

 lects. The red pigment is merely an indicator, for, with excess of water or in the dark, it is 

 not evident. When shoots or roots develop on the lower side of a leaf, this half has a greater 

 dry weight, while, when they develop on both sides, there is no appreciable difference in dry 

 weights of the halves. The explanations offered are that gravity affects the distribution of 

 sap, tending to cause it to collect more on the lower side, and that the organs thus favored 

 grow a little more quickly than the others and tend to inhibit growth of similar organs in other 

 places. Immersion of leaves in water eliminates the influence of gravity. — Otis F. Curtis. 



1355. Loeb, J. Quantitative laws in regeneration. II. Jour. Gen. Physiol. 2: 651-657. 

 1920. — Continuing work previously reported the author gives data to confirm a previous state- 

 ment that a piece of stem inhibits the growth in notches of Bryophyllum because necessary 

 materials move from the leaf to the attached piece of stem. Under the conditions of the ex- 

 periment the gain in weight of the stem was about 14 per cent more than the weight of shoots 

 and roots that would have been produced from the notches if the leaf had been isolated. 

 The distribution of a red pigment served as an indicator of the distribution of necessary 

 materials. — Otis F. Curtis. 



TEMPERATURE RELATIONS 



1356. Northrup, John H. Concerning the hereditary adaptation of organisms to higher 

 temperature. Jour. Gen. Physiol. 2: 313-318. 1920.— See Bot. Absts. 5, Entry 433. 



1357. Northrxjp, John H. A device for regulating the temperature of incubators either 

 above or below room temperature. Jour. Gen. Physiol. 2: 309-311. 1920. — The temperature 

 is controlled by means of a relay which regulates the flow of water through the jacket of a 

 double-walled incubator. The relay directs the stream of water either through the incubator 

 or to the waste pipe as required by the temperature changes. Either hot or cold water may 

 be used depending on the temperature desired. — H. E. Knowlton. 



RADIANT ENERGY RELATIONS 



1358. de Besteiro, Dolores C, and Michel-Durand. Influence de l'eclairement 

 sur l'absorption du glucose par les racines des plantes superieures. [Influence of light 

 intensity on the absorption of glucose by the roots of higher plants.] Rev. Gen. Bot. 31 : 94-108. 

 1919. — The effects of four different light intensities, namely: J, f, §, and full sunlight were 

 determined, using Pisum sativum, grown singly in water cultures, with the roots growing under 

 sterile conditions. The authors found that when the tops were grown in a limited supply of 



