3°° 



BOTANICAL GAZETTE 



[APRIL 



the surface of the soil, it was maintained 



gulating 



amount 



in the surrounding vessel. 



grow 



an abundant supply of water. All were grown under these con- 



differed 



they 



measurements 



made throughout the experiment 



L measurements made 

 The results are shown 



close longitudinal sections were made ir 

 grown under the different conditions, a 

 of the distances between the diaphragms. 



in the tables. 



Effect on growth. — From table II it might be concluded that 



a change from water to air retards growth, and the reverse change 



accelerates it. Two 

 facts, however, must be 



noted: (i) in some cases 

 in the same pot one 



Culms ace el. 9 

 Culms retard. 11 



15 

 6 



1 

 19 



15 



A 



11 



5 

 11 



Fig. i. — Effect of temperature and surrounding 

 medium upon growth of culms of Stir pus validus. 



culm was growing faster 

 after the change, while 

 another was growing 

 more slowly; and (2) the 

 temperature was not 

 controlled . Toward the 

 latter part of the experi- 

 ment an effort was made 

 to keep a record of the 

 variation in tempera- 

 ture. A recording ther- 

 mometer was not avail- 

 able, consequently four 

 thermometers were hung 

 at different points 



among the plants and an average taken. As the greenhouse was 

 supposed to be between 60-70 F., the readings were taken about 

 2:00 p.m. each day, merely to note any marked change in tem- 

 perature. It was found, however, that the variation was too great 

 and the readings too far apart to make the data of any value 



