Imbibition and Growth of Opuntia. 



141 



*'Ao Sodium hydroxid 

 Nutrient solution 

 Distilled water 

 %o Hydrochloric acid 

 %o Malic acid 



%o Hydrochloric acid 



12 

 Time in hours 



Fio. 30. — The course and amount of swelling of sections of Opuntia in solutions as indicated dur- 

 ing a period of 24 hours. Fresh sections 12 mm. across were cut from green joints and placed 

 in glass dishes in a dark room at 18° C. The lines are traced from the results of measure- 

 ments made at 6-hour intervals. Compare with fig. 31. (Redrawn after E. R. Long.) 



50 



Nutrient solution 

 Distilled water 



'ifoo Sodium hydroxid 



'^o Malic acid 



•y^oo Hydrochloric acid 



April 10 13 16 20 23 27 30 



Fig. 31. — Record of growth of flower-buds of Opuntia, on joints the bases of which were immersed 

 in solutions, the imbibition effects of which are shown in fig. 30. The record covers a period 

 of three weeks, or the entire measurable period of extension of the buds to the time of open- 

 ing. The preparations stood in a glass house and were exposed to alternating conditions of 

 daylight and darkness and to temperatlres of about 15° to 30° C. (See fig. 30.) (Redrawn 

 after E. R. Long.) 



