CURRENT LITERATURE 



NOTES FOR STUDENTS 



Permeability. — Further evidence against Czapek's theory of protoplasmic 

 permeability is offered by Miss Williams.' who finds that immersion of tissues 

 of Saxifraga umbrosa in certain electrolytic solutions, aluminum, potassium, and 

 barium chlorides, potassium and barium nitrates, produces abnormal permea- 

 bility to 0.2 per cent ferric chloride. Penetration was evidenced by reaction 

 with tannin. The time of immersion required to bring about the change varied 

 somewhat with the electrolyte, and greatly with the concentration employed. 

 In all the electrolytes used, except barium chloride, plotting logs of time against 

 logs of concentration in gram-mols per liter gave approximately straight lines. 

 The abnormal permeability to iron chloride was induced without rendering the 

 protoplasm permeable to colored cell sap in certain cells, and at surface tensions 

 far from that considered critical by Czapek. — C. A. Shull. 



Colorimeter and indicator method. — Duggar^ and Dodge have devised 

 a method of obviating the interference of colored biological fluids with the 

 indicator method of Ph determination. This is accomplished by placing 

 equal layers of the colored test fluid on each side of a colorimeter; that on 

 the left side receives the indicator, that on the right serves simply as a color 

 blank. Equal layers of standard solution are also placed on each side; that 

 on the right receives the indicator, that on the left serves as a blank. — ^J. J. 

 Willaman. 



Flora of the Congo. — ^Wildeman^ has resumed the publication of his 

 studies of the Congo tlora, which is prolific in new species. In the 5 fascicles 

 just distributed, 334 new species are described, representing 39 families. The 

 most largely represented families are Orchidaceae with 58 new species (27 of 

 which belong to Angraecum) and Gramineae with t,t, new species. Only 2 

 new genera are described, one in Leguminosae {Pynaertiodendron) , and the 

 other in Cucurbitaceae (Bambekca). — J. M. C. 



' Williams, Maud, The influence of inunersion in certain electrolytic solutions 

 upon permeability of plant cells. Ann. Botany 32:591-599. 1918. 



^ DuGGAR," B. M., and Dodge, C. W., The use of the colorimeter in the indicator 

 method of H ion determination with biological fluids. Ann. Mo. Bot. Gard. 6:61-70. 

 1919. 



^ VViLDEMAX, E. DE, Florae Congolensis. Bull. Jard. Botanique Bruxelles 

 4:361-429. 1914; 5:1-108. 1915; 5:109-268. 1916; 6:1-129. ph. 3S. 1919. 



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