1914] Isaac King Phelps 445 



Partition of the nitrogen o£ plant, yeast and meat extracts. 



F. C. Cook. {Animal Physiol. Lab., Bur. of Chem., U. S. Dep't 

 of Agric.) There is great Variation in the precipitating power of 

 the different reagents compared. Phosphotungstic acid precipitated 

 the highest, tannin salt reagent the next highest, and acid-alcohol the 

 lowest, percentage of the nitrogen of the seven plant, five meat and 

 one yeast extracts examined. The formol titration method gave 

 lower results for amino nitrogen than the Van Slyke method. All 

 the methods showed a larger percentage of the nitrogen present in 

 a more completely hydrolyzed State in the plant than in the other 

 extracts. No creatin or Creatinin, and very little purin, nitrogen 

 was found in the plant extracts. The yeast extract was high in 

 content of purin nitrogen but contained no creatin or Creatinin. 

 The nitrogen of the plant extracts was found in the filtrate from 

 the acid-alcohol reagent. Twenty-five percent of the nitrogen of 

 the other extracts was precipitated by this reagent. The plant ex- 

 tracts showed more ammonia by the Folin method than the other 

 extracts. 



The physiological water requirement and the growth of 

 plants in glycocoU Solutions. Alfred Dachnowski and R. 

 G0RMLEY.2 (Lab. of Plant Physiol, Ohio State Univ.) Though 

 it is not known precisely to what extent amino acids occur in peat 

 soils, the question of the ability of plants to utilize directly nitrog- 

 enous Compounds in the soil other than nitrates and ammonia is of 

 considerable importance. The data presented show that the absorp- 

 tion of glycocoll is not connected with the transpirational water loss 

 but with the efficiency of the nutritive metabolism characteristic of 

 the plant, and with the amount of water retained within the plant 

 and involved in metabolism. Changes in body weight, if taken as 

 the measure of growth, may be markedly altered by the quantity of 

 metabolically retained water as well as by the deposition or removal 

 of reserve materials in the tissues. The failure to promote contin- 

 uous growth may be due to the inefficiency of glycocoll to supply 

 material for tissue construction. This and the lack of available 

 water enforce compensating processes in the plant. 



The problem of the water requirement of plants and the criteria 

 for the wilting coefficient, in particular the relation between the 



2 Dachnowski and Gormley : Amer. Jour. Bot., 1914, i, p. 174. 



