78 Journal of Agricultural Research voi. xix.no. a 



OSMOTIC CONCENTRATION 



The osmotic concentrations of the solutions were not determined, 

 because the data on the electrolytic dissociation of the component acids 

 and salts under the variety of reactions used is not available and the 

 authors did not have access to the necessary apparatus for making cryo- 

 scopic determininations. However, the relatively small change in total 

 volume- molecular concentration within either series would indicate that 

 little, if any, difference in growth within a given series should probably 

 be attributed to the osmotic factor. 



WATER EMPLOYED 



All cultures v/ere made from distilled water which had been rendered 

 nontoxic by treating with carbon black as first recommended by 

 Livingston {14). 



TECHNIC OF GERMINATION AND GROWTH OF SEEDLINGS 



The seeds of wheat, soybeans, and corn were germinated by supporting 

 them upon a paraffined wire gauze which was floated by means of corks 

 so that it was just even with the surface of nontoxic distilled water con- 

 tained in a porcelain enameled pan. The seedlings were transferred to 

 the various cultures when the plumules had attained a length of from 4 

 to 5 cm. The alfalfa seeds were germinated upon pads of filter paper 

 in Petri dishes and transferred to the cultures after the seedling had 

 attained a length of about 4 cm. 



The wheat and alfalfa seedlings were grown in Non-Sol and Pyrex 

 beakers holding 250 cc. of culture solution and were supported upon per- 

 forated caps of paraffined cheesecloth according to the method of Haas 

 (7). The corn and soybean seedlings were grown in 8-ounce jars of flint 

 glass and supported with corks according to the method of Tottingham 

 {26). All beakers and jars were covered with black paper to exclude 

 light. The solutions were renewed on all cultures every fourth day, and 

 the glassware was thoroughly cleansed and sterilized before being used 

 again. The reactions of the solutions used for growing wheat seedlings 

 in both series were determined both before and after the 4-day periods. 

 It was found that the successive solutions made up for a given reaction 

 varied from each other by negligible amounts, so the solutions used for 

 the growth of soybean, corn, and alfalfa seedlings were tested only at 

 irregular intervals. 



EXPERIMENTAL DATA AND DISCUSSION OF RESULTS 

 SERIES A 



Wheat seedlings were grown for a period of 1 6 days in solutions having 

 the composition given for series A. Growi:h was determined by taking 

 the green weight of roots and tops, exclusive of seeds. Twelve seedlings 

 were grown in each culture, and all seven cultures of the series were dupli- 

 cated. The duplicate cultures agreed closely in all cases and are there- 



