120 abstracts: plant physiology 



able to regain their turgor unless additional water is supplied (See Bulle- 

 tin 230, Bureau of Plant Industry, 1912, "The Wilting Coefficient for 

 Different Plants and Its Indirect Determination," by L. J. Briggs and H. 

 L. Shantz) . For this purpose wheat seedlings were grown in a series of 

 soils having a graduated salt content, with sodium sulphate as the 

 principal component. 



It was demonstrated that the utilization of all "available" moisture 

 in the soil is not prevented by the presence of "alkali" salts unless in 

 quantity sufficient virtually to inhibit the growth of the plants. While 

 the amount of growth made by the plants decreased regularly with the 

 salt content of the soil, their roots, even in the mixture having the high- 

 est salt content (0.74 per cent of the dry weight of the soil) in which any 

 growth was made, were finally able to reduce the soil moisture to the 

 calculated wilting coefficient. Absorption was much retarded, however, 

 in the more saline soils, the length of time required for the plants to reach 

 the wilting point having ranged from 18 in the soil having the lowest 

 salt content to 43 in the soil having the highest. T. H. K. 



PLANT PHYSIOLOGY. Some effects of refrigeration on sulfured and 

 unsulfured hops. W. W. Stockberger and Frank Rabak. Bul- 

 letin No. 271, Bureau of plant Industry, Department of Agricul- 

 ture, pp. 21. 1912. 

 This bulletin summarizes the results of a comparative study of the 

 effects of cold and ordinary storage on sulfured and unsulfured hops. 

 Trade experts agreed that the samples of sulfured hops in cold storage 

 were best in quality, but differed widely as to the undesirable effect of 

 the treatment upon the other samples. 



Determinations were made of the acidity and ester content of the 

 volatile oils extracted from samples of the hops under each condition 

 of storage. The conclusions drawn from these analyses are that both 

 sulfuring and cold storage retard changes in the hops leading to an 

 increase in acidity and ester content of the oils. Cold storage is appar- 

 ently more effective than sulfuring in retarding the increase in acidity, 

 but is less efficient than sulfuring in retarding increase in ester content. 

 Cold storage and sulfuring combined are much more effective in retard- 

 ing changes in acidity and ester content than either alone. The per- 

 centage of decrease in the content of soft resins was found to be less in 

 the cold-stored hops than in those in ordinary storage. The evidence 

 from the analyses goes to show that the sulfuring tends to retard changes 

 in the content of soft resins only when combined with cold storage. 



W. W. S. 



