i^t> 



_^ ERI ENTS WTJH.OPUITriA. 



2he plants v/ere young natural seedlings of 

 punt i a versicolor collected at Tucson, Arizona, by Dr. 

 ,/. A. Gannon, './hen received in the laboratory the stems 

 were 6 to 10 centimeters long and were in resting condi- 

 tion. They were planted in a soil consisting of two 

 parts sand and one part loam and irrigated with the auto- 

 irrigator, as usual. In the week beginning March 18, 

 1917, new growth began in three of the plants and on 

 March 22, 1917 one of these was sealed and supplied with 

 nitrogen according to the usual technique. Nothing cor- 

 tesponding to wilting could be detected in small plants 

 of this character and the water-intakes of all of the 

 plants were so small in total quantity that variations 

 were undeterminable. However the new leaves of the 

 plant supplied with nitrogen stopped growing immediate- 

 ly and became darker in color, while the growth- rate 

 and color of the new growth on two of the control plants 

 remained normal. After 23 days on nitrogen the roots 

 were examined. All small roots were found to be dead 

 and badly decayed and the lower half of the fleshy 

 main root was also decayed. 



