AGRICULTURAL BOTANY. 825 



dry weight of roots. Mixtures of sodium and potassium inhibited development 

 of both roots and tops in all inhibitory or toxic concentrations to a markedly 

 greater extent than did isosmotic solutions of the pure salts. In stimulatory 

 concentrations the pure salts permitted greater and more normal development 

 than mixtures. Sodium in any proportion decreased the stimulatory effect of 

 potassium. 



For mixtures of sodium with ammoninni, hij:,'hly toxic concentrations per- 

 mitted slightly greater dovoloi)mont when the two ions were present in the 

 ratio of 1:1. For stimulatory concentrations the stinnilating effect was de- 

 creased in mixtures, growth becoming better as the ratio of one ion to the other' 

 increased from 3:1 to G<) : 1. 



The harmful action of distilled water, R. H. True (Abs. in Science, n. ser., 

 S9 (1914), No. 099, pp. 295, 2.W).— Attention is called to the Injurious action of 

 distilled water, the author stating that samples which show the highest resist- 

 ance are in general more harmful to lupine roots than waters containing a 

 large quantity of electrolytes. The primaiy cause of injuiy is said to be the 

 extraction of electrolytes and perhaps of other substances as well. This is 

 regarded as a special case of the general type of injury wrought on cells by 

 unbalanced solutions. The distilled water seems to withdraw the material 

 required for the maintenance of the efficient action of the protoplasmic limiting 

 membranes, with the result that the permeability of the cells is increased and 

 a further dissociation of the electrolytes from their combination in the proteids 

 and other chemical structures of the cell ensues. 



In a subsequent paper the author calls att'^ntion to the need of plant physiolo- 

 gists for a normal physiological solution in which to conduct their experiments. 



Radio-activity and vegetation, M. Yacher (G6nie Rural, 2V"o. 49-50 {1913), 

 pp. 8-12, figs. 4). — This is a somewhat abridged form of an article previously 

 noted (E. S. R., 30, p. 29) from another source. 



The physiology of the rest period in potato tubers, C. O. Appleman (Abs. 

 in Science, n. ser., 39 (1914), No. 999, p. 294).— The author claims that the rest 

 period of potato tubers is not firmly fixed and hereditary, as it may be elimi- 

 nated by various agencies. 



Biochemical study of after-ripening in the potato tuber, C. O. Appleman 

 (Abs. in Science, n. ser., 39 {1914), No. 999, p. 2P//).— Attention is called to the 

 fact that under normal conditions potato tubers will not sprout for several weeks 

 after harvest, or until certain changes have taken place in the buds or their 

 immediate environment. These changes are spoken of as after-ripening. 



In the author's experiment tubers were cut in half and analyses made sepa- 

 rately of the seed and stem halves, with the view to detecting the chemical 

 changes characteristic of after-ripening. The carbohydrate transformations 

 were dependent entirely upon changing temperatures. Active diastase was 

 present at all stages of the rest period and showed no increase during natural 

 after-ripening. Protein, lipoid, organic extractive, and inorganic phosphorus, 

 calculated as total phosphorus, each remained constant up to the time of sprout- 

 ing. It appears that after-ripening does not involve proteolysis or other changes 

 in the various nitrogen combinations. 



The metabolic changes involving the above substances as well as others are 

 said to begin rather suddenly, are concurrent with sprouting, and are therefore 

 not primary processes of after-ripening. 



Metabolic changes in potato tubers during sprouting, C. O. Appleman 

 (Abs. in Science, n. ser.. 39 {1914), No. 999, pp. 293. 2.''//).— The author pre- 

 sented an account of investigations the practical application of which hns been 

 noted elsewhere (E. S. R., 29, p. 230). 



