Books and Current Literature. 1^1 



Prof. H. H. Dixon and Mr. W. R. G. Atkins, of Trinity Col- 

 lege, Dublin, have described a thermo-electric method of deter- 

 mining freezing points of solutions in the scientific proceedings 

 of the Royal Dublin vSociety for February, 1910, by which they 

 are able to determine the ostnotic pressure of sap of plants very 

 readily. Twent\ -three species were tested by the new method 

 and it was found that the osmotic pressure varies considerably 

 in different individuals of the sa'r.e species and in the same indi- 

 vidual under different circumstances. The leaves showed an 

 osmotic pressure of nearly 27 atmospheres while the roots, which 

 generally had a much lower pressure, ranged from four to six 

 atmospheres. The authors surmise that the leaves of Syringa 

 may have the sap concentrated by evaporation to a pressure of 

 30 or 40 atmospheres before they begin to wilt. 



Strakosch, in the Berichte of the Vienna Academy, contrib- 

 utes a short paper on the climate of Egypt and the Egyptian 

 Soudan from the standpoint of photochemistry. Fie concludes 

 that the chemical intensity of light in that region does not in- 

 crease proportionally with the height of the sun, and that at a 

 given height of the sun it is less than in Middle Europe. This is 

 attributed to the infrequent rains in Egypt and the Soudan. 

 Fine particles of dust which rise to great heights and the greater 

 nearness to the equator with its thicker at .iiospheric strata are 

 also held to be factors. 



Jaccard's earlier researches on the floral distribution of 

 alpine meadows have been supplemented by later studies of 

 subalpine micadows. His work has been conducted on natural 

 meadows at a height of 1,200 meters, in theWoadtlaender Alps, 

 where 52 areas, each containing one square meter, were em- 

 ployed in the investigation. His work is reported under the 

 following heads: 



1 . Elementary floral differences. 



2. Relative frequency of the species of an association. 



3. Relation between local and general frequency. 



4. Curves of local frequency on the meadows of the south- 

 ern Jura. 



5. Relative general frequency. 



6. Individual frequency. 



