3lb Physiologie. 



donc une preuve definitive de la formation de toutes pieces du pig. 

 ment anthocyanique dans les fleurs de Cobaea scandens. 



Dans les feuilles d^ Ampelopsis hederacea, le pigment rouge se 

 forme en automne, en grande partie de toutes pieces et en partie 

 par transformation d'un pigment jaune preexistant En effet, 10 

 kilogr. de feuilles vertes recoJtees avant le rougissement ont fourni 

 4,73 gr de pigment jaune cristallise et pas de pigment rouge. 10 

 kilogr. de feuilles rouges recoltees apres le rougissement complet 

 ont fourni 18,91 (4 fois plus) de pigment rouge cristallise et pas de 

 pigment jaune. II y a donc eu, au cours du rougissement, trans- 

 formation du pigmeiit jaune en pigment rouge (transformation que 

 l'auteur a pu reproduire in vitro, par reduction) et formation de 

 toutes pieces de la plus grande partie du pigment rouge. 



II resulte de ces recherches que. dans certains cas (coroUe de 

 Cobaea scandens). la totalite du pigment anthocyanique se forme de 

 toutes pieces; dans d'autres (feuilles d^Atnpelopsis hederacea), une 

 petite partie du pigment rouge resulte de la reduction d'un pigment 

 jaune preexistant, la plus grande portion s'etant formee de toutes 

 pieces. R. Combes. 



Falk, K. G., Studies on enzyme actio n. IV. Note on the 

 occurrence of urease in castor beans. (Journ. Am. Chem. 

 Soc. XXXV. p. 292. 1913.) 



The presence of urease in the seed of the castor bean [Ricinus) 

 is demonstrated. G. L. Forster (St. Louis). 



Giddings, L. A., Transpiration of Silphium laciniatum L. 

 (Plant World. XVII. p. 309-328. f. 1—10. 1914.) 



A study was made of the relation between the transpiration of 

 this prairie plant and the evaporating power of the air. Detached 

 leaves were used in the transpiration studies, and the evaporation 

 was measured with the Piche atmometer. The factors influencing 

 the evaporating power of the air — wind velocity, humidity, and 

 temperature — were also measured. Evaporation was found to in- 

 crease with height above the ground, principally because of increa- 

 sed wind velocity. Experiments in the laboratory showed that the 

 rate of evaporation and also of transpiration, within limits, varied 

 in an almost direct ratio with increase in wind velocitj-. The ability 

 of the leaves of Silphium to give off water by transpiration was 

 found to Vary with their position on the stem. The upper leaves 

 have a smaller area than the lower and they are able to give otf 

 water less rapidly per unit area than those nearer the ground. 



Sam. F. Trelease. 



Goodspeed, T. H., Notes on the germination oftobacco 

 seed. (Univ. Calif. Pub. Bot. V. p. 199—222. 1913.) 



Treatment with 70-80 per cent H2SO4 for lengths of time varying 

 from 5 — 15—20 minutes markedly increases the percentage germi- 

 nation and in many cases hastens the time of germination of the 

 seeds of a number of species of Nicotiana. Prolonged washing of the 

 treated seeds tends to lower the percentage germination. 



W. H. Emig (St. Louis). 



Levaux, H., Deformation des touffes de Bruyeres au 



