Jane, 1920.] SOME SOLUTION CULTURES OF WHEAT 79 



carried five seedlings, and was fitted into the mouth of a " pint 

 Mason " jar of hard glass, which held the nutrient solution (about 

 440 c.c). The jars were covered with paper jackets such as were used 

 by Shiye, to exclude most of the light, and all stood on a continually 

 rotating table in one of the greenhouse rooms of the Laboratory of 

 Plant Physiology of the Johns Hopkins University, at Baltimore. Tem- 

 perature, evaporation 1 ^ and sunshine (radio- atmometer) records were 

 obtained for the experimental period, which lasted from January 28 to 

 February 20, 1920. The temperature for the period ranged between a 

 minimum of 11° and a maximum of 30°C. The total corrected loss 

 from a Livingston standard white spherical atmometer (located on the 

 rotating table with the cultures) was 456.1 c.c. for the period. The 

 radio-atmometric difference (corrected loss from black sphere minus 

 corrected loss from white) was 4.4 c.c. for the period. The last two 

 data show that the evaporating power of the air in the culture room 

 was relatively low and that the sunshine intensity was very low 

 indeed. 



The solutions were renewed after ZV2 days, at the end of the first 

 week and at the end of the second week. A single culture represented 

 each of the 90 different incomplete solutions tested, and six control 

 cultures were provided with a solution that was complete and well- 

 balanced for the early stages of wheat. The control solution used was 

 Shive's R5C2 (1.75 atmospheres), having the following partial volume- 

 molecular concentrations (gram-molecules per liter) of the three main 

 salts: KH 2 P0 4 , 0.018; Ca(N0 3 ) 2 , 0.0052; MgSQ* 0.015. Of course 

 these controls, as well as all the experiment, solutions, contained a 

 small amount of iron ; about 3 mg. of suspended FePO., was added to 

 each culture jar at the beginning and at every renewal of solution, in 

 the manner followed by Shive. 



The 90 different solutions without- potassium (all having a total 

 salt content of 0.015 gram-molecule per liter— of all salts taken to- 

 gether—and an osmotic-pressure value of about 1.00 atmosphere) were 

 grouped in six series of fifteen solutions each, each series representing 

 fifteen different sets of proportions of a single set of three salts. There 

 were thus six different .sets of salts, all that are logically possible on 



1) Standardized spherical porous-cup atmometers were employed ; regarding at- 

 mometry, the porous-cup atmometer and the radio-atmometer, see: Livingston, B. 

 E. Atmometry and the porous cup atmometer. Plant World 18:21-30, 51-74, 95- 

 111, 143-149. 1915. Idem. Atmospheric influence on evaporation and its direct 

 measurement. Monthly Weather Rev. 43 : 126-131. 1915, 



