13 



The practical value of such a development of these studies is indi- 

 cated by certain conditions to which agriculture in alkali regions is 

 subject. It is well known that while at the beginning of the season 

 the salt components are often pretty equally distributed through a 

 considerable depth of soil and are in consequence comparatively harm- 

 less, the increased evaporation which accomi)anies increased temi>er- 

 atures and decreased atmospheric moisture as the season advances 

 draws these salts to the surface of the soil, where they often effloresce 

 and form "'crusts" (especially in the case of sodium carbonate and 

 sodium sulphate). Hence older plants are frequently exix)sed to the 

 action of much more concentrated solutions than the same individuals 

 when younger had to contend ^sith. Furthermore, the accidents of 

 irrigation may materially alter the alkali content of a soil in the midst 

 of the growing season of a crop. It is therefore to be hoped that this 

 important extension of the investigation may soon receive attention. 



DETAILS OF MANIPULATION. 



The manner of preparing the solutions and the plants to be culti- 

 vated has already been described. A few words about methods and 

 details followed in the experiments are in order. 



To contain the solutions, glass vials nearly 3 cm. in diameter and 

 holding about 70 c. c. of liquid were used. In the experiments with 

 lupines, only one plant was suspended in each vial by means of a hole 

 lx>red through a close-fitting thin cork stopper, the aperture being 

 entirely closed by means of cotton batting. Protection against undue 

 evaporation from the upper portion of the plant was secured by plac- 

 ing several ^ials in a glass jar containing a little water and inverting 

 another jar over the whole. The plant was so adjusted in the cork 

 that 1 to 3 cm. of the terminal portion of the radicle was Immersed in 

 the solution, the uppeiTiiost portion of the radicle extending through 

 the vapor-saturated space between solution and stopper, while the 

 hj-pocotylarj' section was invested with moist cotton. 



In the case of alfalfa five or six x^lants were inserted in each vial in the 

 following manner: A piece of aluminum wire was passed through the 

 cork stopper in such a way as to allow it to be raised or lowered at discre- 

 tion. On the portion of the ^vire included in the vial five or six small 

 loops were made of proper size to hold in place each a seedling plant, with 

 its seed leaves resting on the loop and its root immei*sed in the solution. 



The duration of the culture in the salt solution was generally lim- 

 ited to twenty-four hours, as it was usually possible at the end of that 

 period to determine accurately whether the root ti\) had been killed 

 or not. Frequenth", however, the plants were returned to the solution 

 for a second period of equal duration in order to remove all doubt 

 upon this point. ^ If at the end of that period no growth had taken 



' In this particnlar, as in others, the experimental methods outlined by Kahlen- 

 berg and Tme [Bot. Gazette. 22, 87. 9U (1896)] have been followed, as it was 

 desirable to make as close comparison as possible with their results. 



