height and a tall upper part which fits down over the former 

 leaving an air space of one centimeter between the lower 

 and upper parts. By this means all light was excluded but 

 air exchange was not prevented. These small cases were 

 placed in special large constant temperature cases designed 

 by Professor Charles F. Hottes. The seedlings were re- 

 moved from the cases daily, measured and watered. Dur- 

 ing the period of measuring, approximately ten minutes, 

 the seedlings were exposed to the light and to the temper- 

 ature (20 C) of the laboratory. Seedlings deformed or 

 otherwise abnormal were discarded. They were grown in 

 series at temperatures 20, 25 and 30 C. The large seeds, 

 of which only a very limited number were on hand, were 

 grown at 25 C only. 



All measurements were taken beginning two and one- 

 half centimeters above the root origin. If the entire height 

 of the shoot is desired, two and one-half centimeters must 

 be added to the total height of the shoot as recorded in the 

 tables. In those cases in which the cotyledons were not 

 opposite, the length of the hypocotyl was measured to the 

 insertion of the lower cotyledon. The length of the inter- 

 nodes were taken from the lower part of one node to the 

 lower part of the next higher or, in the case of the upper 

 internode, to the growing point. A centimeter rule was 

 used and the measurements were read to the nearest milli- 

 meter. From the record of these daily measurements, the 

 daily growth increments given in the tables were obtained. 



When a shoot showed no growth since the previous day 

 its diameter, one centimeter below the insertion of the coty- 

 ledons, was taken by means of a vernier callipers. The 

 seedling was then removed from the soil or the water, the 

 root was washed, superficially dried, and separated from 

 the shoot. Then the fresh weights of root and shoot were 

 obtained. These parts were dried to constant weight in an 

 electric oven. All weights were read to the fourth decimal 

 place. 



The data for the several series are given in * Tables 1 to 

 47. Data are given for individual seedlings grown at the 

 temperature 25C; for those grown at 20 and 30C, the 



