210 



several weeks to grow; then above the stunted portion strong leaf stalks shot 

 upward, and in three weeks had attained a height twice as great as the stunted 

 portion had reached in two months. The leaves of plants grown under normal 

 conditions were alternate. 



The effect of drought on the Canna was not as immediate as in case of the 

 Oxalis, not causing wilting, but in time became more decided because of the 

 changed position of the leaves. 



The structural ditierences were quite apparent. In a strip of epidermis taken 

 from the leaf of a normal plant the cells were irregular and angular; the angles 

 were held firmly in position b}' the turgescence. The guard cells showed a firm 

 outline. The stomal openings were quite narrow. The stomata were slightly more 

 numerous under drought, being 600 per inch, in normal plants 400 per inch. The 

 stomata openings were also wider in drought. See figures 3 and 4. 



The common bean will apparently withstand more drought than any of the 

 plants examined. The general appearance of the plant was not materially 

 changed. The growth, however, was retarded by drought, the stalk only growing 

 half as long as the stalk of normal plant in the same length of time. The shorter 

 stalk was also larger in diameter. The plant grown under favorable conditions 

 was more flexible, not because of lack of turgescence, but because of lack of thicker 

 cell walls developed by drought. 



The plant cells were smaller and less turgescent when subjected to drought. 

 The stomata were increased in number, the guard cells metamorphosed, and the 

 stomal openings larger than those of plants grown in moisture. 



The trichomes of the bean are not branched, and are of the non-glandular 

 variety. When subjected to drought they remain shorter, and the diameter is 

 increased slightly. 



In a cross section of the stem of plants subjected to drought, the non- 

 turgescence of the cells was shown, also a slight thickening of the cell walls. This 

 thickening was demonstrated by the time required for the iodine to penetrate the 

 .cell walls as compared with the walls of cells grown in favorable conditions. See 

 figures 5 and 6. 



The general appearance of corn showed the effects of drought more in change 

 of color and the tendency of the leaves to twist and wrinkle lengthwise. The 

 growth was also stunted. 



The epidermis was more difficult to separate from the underlying tissue of 

 plants subjected to drought than from plants under normal conditions. The char- 

 acteristic difference in turgescence of the cells was shown, also metamorphosed 

 guard cells and stomata. See drawings, plates 7 and 8. 



