FIELD CROPS. 231 



occurred. The aerial parts proved liiglily resistant to its action, showing no 

 general response either in stems or foliage, nor was photosynthesis influenced 

 by the rays. The pollen grains gave diverse results, some not growing at all, 

 while others gave no reaction whatever to the rays. 



The movements of protoplasm which were studied in the aerial hairs of the 

 pumpkin, the internodal cells of Chara, and in the leaf cells of Elodea cana- 

 densis, were absolutely unaffected by the radium rays. 



The acid content and acid resistance of various roots, K. Aso {Flora, 100 

 (1910), No. 2, pp. 311-316). — A preliminary report is given of investigations on 

 the acid content and acid resistance of various plants. Roots of seedlings of 

 mustard, peas, lupines, oats, barley, buckwheat, spinach, and potatoes were 

 placed in solutions containing from 0.1 to 0.01 per cent of citric acid, and the 

 behavior of the plants noted. 



The greatest dilution of citric acid was found to be quite injurious to spinach, 

 mustard, and peas, while its noxious effect was delayed somewhat with lupines, 

 barley, oats, and potatoes. In general the plants in the earlier stages appeared 

 somewhat more resistant to the acid than in the later stages, when the root 

 hairs had been developed and chlorophyll functions had begun. 



The resistance to sodium nitrite was investigated with cultures of mustard, 

 lupines, peas, oats, potatoes, and buckwheat, and the amount of injury was 

 found to be inversely proportional to the acid content of the roots. 



The resistance of Medicago seed to hig'h temperatures, O. Schneider- 

 Orelli (Flora, 100 (1910), No. 2, pp. 305-311). — Experiments were conducted 

 with seeds of a number of species of Medicago to test their resistance to dry 

 and moist high temperatures. 



The seeds of some of the species are characterized by the hardness of the 

 seed coats, and practically all such resisted temperatures approximating that 

 of boiling water. In some instances the treatment favored the germination. 



In one of the experiments one lot of seed was filed to cut through the hard 

 seed coat, another placed in concentrated sulphuric acid for half an hour, while 

 a third was untreated. More than | of the treated seed germinated, while 

 only 3 out of 20 in the check lot sprouted. The ungerminated seed were 

 then filed, after which 15 out of 17 sprouted. 



The experiments showed remarkable resistance to high temperatures on the 

 part of seeds of Bl. denticulata and M. arabica, some of which germinated after 

 17 hours' exposure to a temperature of 100° C. or a half hour at 120°. A 

 temperature of 130° destroyed all the seed. A small portion of the seed ger- 

 minated after remaining 7J hours in boiling water, or i hour in water heated 

 in an autoclave to 120°. After the seed coats had been made permeable by any 

 of the treatments the seeds were found to quickly lose their resistance to high 

 temperatures. 



The source of the drug- Dioscorea, with a consideration of the Dioscorese 

 found in the United States, H. H. Bartlett (U. S. Dept. Agr., Bur. Plant 

 Indus. Bui. 189, pp. 29, figs. 8). — The taxonomic history of the Dioscorese of the 

 United States is given, together with a synopsis of the species of Dioscorea 

 and a discussion of the drug Dioscorea, with illustrations showing the various 

 types of rhizomes now on the market. 



FIELD CROPS. 



A study of cultivation methods and crop rotations for the Great Plains 

 area, E. C. Chilcott (U. S. Dept. Agr., Bur. Plant Indus. Bui. 187, pp. 78, pi. 1, 

 fig. 1). — This bulletin reports the results of 18 comparative tests at 11 stations 

 in the Great Plains area, 3 years' results being obtained at Edgeley, N. Dak., 



