Physiologie. 405 



of CaCOa to the NaNOg Solution produced only a slight increase in 

 the dry weight. In the KCl Solution all of the potassium was removed 

 leaving the Solution acid. Growth was very slight in all the acid 

 Solutions. However the presence of CaCOs in the case of KCl and 

 HCl overcame the injurious effects of the acids in the Solutions. 



W. H. Emig (St. Louis), 



Brown, W. H., The mechanism of curvature in the pulvini 

 of Mimosa piidica. (Phillipine Jour. Sei. VII. p. 37—40. 1913.) 



The author experimented with the pulvini of the leaflets of 

 Mimosa after they had been killed in boiling water. By coagulating 

 the Proteids of the cells around the osmotically active substances, 

 osmotic cells were formed. The pressure of these was then reduced 

 by replacing the water in them with some liquid, as xylene, in 

 which the osmotically active substances would not dissolve. In this 

 way a reaction of the dead pulvini was obtained. The results support 

 Pfeffer's conclusion concerning the mechanism of the movement 

 in the pulvini of the petiole of this plant. 



L. 0. Overholts (St. Louis). 



Brown, W. H., The relation of the substratum to the 

 growth oi Elodea. (Phillipine Jour. Sei. VIII. p. 1—20. 1913.) 



The author reports the results of a series of experiments planned 

 to Show the importance of a soil substratum for the growth of 

 Elodea. It was found that the amount of CO2 that normally diffuses 

 into water from the air is not sufficient for growth. The presence 

 in the cultures of soil rieh in organic substances serves as an 

 important source of COg. When plants are rooted in such a soil the 

 maximum growth is obtained. This is not due to any absorbing 

 function of the roots, but results because the plant is thus held 

 close to the lower layer of water where the COo is present in more 

 concentrated Solution. L. O. Overholts (St. Louis). 



Cannon, W. A., Structural relations in xenoparasitism, 

 (Am. Nat. XLVL p. 675-681. 1912.) 



An artificial parasite was obtained by growing Cisstis ladmata 

 on Opuntia Blakeana. The structure of the parasitic roots formed 

 by the Cissus was compared with the structure of the free living 

 roots of the same plant. A like comparison was made between the 

 tissues of the host plant. A short tabulated comparison is also given 

 between the structural characteristics of an haustorium, of an 

 habitual parasite and the analogous absorption organ of an artificial 

 parasite as Cissus. L. O. Overholts (St. Louis). 



Faber, F. C. von. Physiologische Fragmente aus einem 

 tropischen Urwald. (Jahrb. wiss. Bot. LVI. (Pfeffer- Festschrift), 

 p. 197—220. 1915.) 



Die Beobachtungen beziehen sich auf die Transpiration von 

 Krautpflanzen und Bäumen des Urwalds von Tjibodas, auf die 

 Wachstumsgrösse von Urwaldkräutern und auf ihre Assimilations- 

 vorgänge. Der Wasserverlust der Krautpflanzen durch Wasser- 

 dampfabgabe ist im Allgemeinen sehr gering; aber kleine Schwan- 

 kungen in der Intensität des diffusen Lichtes sind im Stand die 

 Transpiration bedeutend zu erhöhen. Die Guttation scheint ein Er- 



