Imbibition and Growth of Opuntia. 



141 



50 



40 



i30 



S20 



10 



%o Sodium hydroxid 

 Nutrient solution 

 Distilled water 

 Itioo Hydrochloric acid 

 %o Malic acid 



■^50 Hydrochloric acid 



12 



Time in hours 



18 



24 



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

 ing a period of 24 hours. Fiesh sections 12 mm. across were cut from gieen 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 weter 



'Jfoo Sodium hydroxid 



"^0 Malic acid 



"^oo Hydrochloric acid 



40 



«30 

 E 



2 

 O 20 



10 



AprillO 13 16 20 23 27 30 



Fio. 31. — Record of growth of flower-buds of Ovi''>i<i'"''< 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.) 



