426 EXPEKIMENT STATION EECORD. 



of the component salts iu nutrient solutions and the alterations of this influence 

 produced by different total concentrations. 



Preliminary to the investigation a study was made of methods for preparing 

 Knop's nutrient solution. The wheat seedlings were started in water, after 

 which they were grown for 24 days in the above solution containing various 

 concentrations of potassium phosphate, magnesium sulphate, calcium nitrate, 

 and potassium nitrate. It was found convenient to employ the component salts 

 of Knop's formula in stock solutions, one part containing only the calcium 

 nitrate and the other part the remaining three salts. Methods for germinating 

 seeds and mounting seedlings in culture solutions, which were somewhat differ- 

 ent from those usually employed, were devised and are described. 



The most important factor found to affect the physiological influence of vary- 

 ing proportions of the four salts in the culture solutions was apparently the 

 ratio of the magnesium content to that of calcium. The injurious effect of 

 magnesium and the amount of dry matter produced by the plants were found 

 to depend upon the complex balance between all the salts in solution. The 

 effects upon growth of any given set of proportions of nutrient salts in the 

 medium varied with the total concentration of the medium. 



A bibliography is given. 



The functions of nutritive materials in higher plants, K. Faack (Mitt. 

 Landw. Lehrkanz. K. K. Hochsch. Bodenkul. Wien, 1 (1913), No. 4, pp. 4^3-509, 

 fig. 1). — Results are given in considerable detail of studies carried out with 

 wheat plantlets as affected by solutions of salts containing nitrogen, carbon, 

 potassium, iron, phosphorus, and sulphur employed separately, and also as 

 furnished simultaneously by placing portions of the rootlets of a given plantlet 

 in different media. It is thought that the nutritive substances necessary to 

 growth must be first combined in and by the plant body itself after being taken 

 np separately in the transpiration current, since passage from root to root is 

 excluded by the arrangement described. 



A short bibliography is appended. 



A review of recent investigations on the mineral nutrition of fungi, A. W. 

 Dox (Biochem. Bui., 3 (1914), No. 10, pp. 222-228).— K critical review is given 

 of recent literature pertinent to the nutrition of fungi, most of the articles 

 having apiieared within the last two years. 



The carbon nutrition of plants, P. Ravin (Ann. 8ci. Nat. Bot., 9. ser., 18 

 (1913), No. 5-6, pp. 289-451, figs. 24). — ^A study is reported on the carbon nutri- 

 tion of radishes grown in Knop's solution, to which were added various organic 

 acids and organic acid and neutral compounds of potassium. The effect of the 

 different compounds on turgescence, respiration, increase in fresh and dry 

 weight, and ash content is shown. 



In addition to radishes, the study was supplemented with investigations on 

 the carbon nutrition of some algae and fungi. For the higher plants it was 

 found that they absorbed and assimilated succinic, malic, citric, tartaric, and 

 probably oxalic acids. The order in which they are mentioned is iu a decreas- 

 ing proportion as to their nutritive action or an increasing ratio of toxicity. 

 If two organic acids, one in a free acid state and the other in the form of a 

 corresponding salt, are added to solutions, the free acid is found more toxic 

 and less nutritive than its corresponding salt. 



Some physiological differences were noted in the behavior of the various 

 groups of plants. Phanerogams were found to utilize indiscriminately the free 

 organic acids and their various potassium compounds. Algae, which are very 

 susceptible to acids, assimilated only the neutral salts of potassium. The molds 

 utilized the organic acids, but not all the organic acid salts. 



An extensive bibliography is given. 



