Physiologie. 243 



object the dermination of the differences in water requirement 

 exhibited by the more important crop plants and some of their 

 varieties with a view to determining those which are most efficient 

 in the use of water under the semi arid conditions existing in the 

 Great Plains. The experimental plants were grown in large pots 

 having a capacity of about 115 Kilos of soll. The pots were provi- 

 ded with tight covers, with openings for the plants, the space 

 between the cover and the stem of the plant being sealed with wax. 

 The loss of water was ihus limited to that occurring from the 

 transpiration of the plants. Water was added, adequate aeration 

 was provided and the plants were grown under screens to prevent 

 injury from hailstones. The results are given in 21 tables. The 

 second buUetin gives a review of the literature and is more than a 

 bibliography as the results obtained by previous workers are given 

 in some detail. Harshberger. 



Brush, W. D., The Formation of Mechanical Tissue in 

 the Tendrils of Passiflora caerulea as influenced by ten- 

 sion and contact. (Botanical Gazette. LIII. p. 453—477. 1912.) 



A histological study of tendrils of Passiflora caerulea under 

 tension and not under tension, and in contact with substances and 

 not in contact led to some conclusions. Tendrils which have been 

 subjected to contact or tension are stronger than those not subjec- 

 ted. The increased strength is due to increase in number and thick- 

 ness of xylem cells in case of contact, and to a thickening of the 

 walls of pith cells in case of tension. Contact is the more important 

 factor, but the strength is greatly increased by the addition of the 

 tension factor. Charles J. Chamberlain (Chicago), 



Dixon, H. H. and W. R. G. Atkins. Osmotic Pressures in 

 Plants. III. The Osmotic Pressure and Electrical Con- 

 ductivity of Yeast, Beer, and Wort. (Notes Bot. School 

 Trinity Coli. Dublin. II. p. 173—176. 1913.) 



The authors point out that in view of the rapid metabolism of 

 the yeast-cell as regards carbohydrates, a study of the osmotic 

 equilibrium between it and the Solution which it ferments is of 

 interest. Paine showed that alcohol penetrates the yeast-cell readily, 

 a State of equilibrium being soon reached in which the ratio of 

 alcohol in the cell to that outside is a constant, deviating only 

 slightly from 0.85; while salts penetrate to a small extent, the ratio 

 between the internal concentrations being no more than 0.1—0.25 

 except in the case of poisonous substances. The authors find that 

 pressed j^east gives much higher values for osmotic pressure and 

 electrical conductivity than does wort, but during fermentation the 

 osmotic pressure increases considerably until that of the beer 

 approaches that of the pressed yeast. When yeast is allowed to 

 stand for 6—24 hours after Separation there is great diminution of 

 osmotic pressure, which may fall below that of the beer from which 

 it was removed. This diminution of pressure is under ordinary cir- 

 cumstances made good by the diffusion inwards of sugar from the 

 wort, hence this carbohydrate must be able to pass freely into the 

 yeast cell while the alcohol produced passes out, maintaining a 

 "constant ratio. F. Cavers. 



