245 



of various degrees of saturation through the chamber, and by 

 means of the bubbles the rate of transpiration can be determined. 

 One can demonstrate the effects of ordinary laboratory air on 

 transpiration or the effects of dry and moist air. The effects of 

 dry air may best be determined by aspirating through sulfuric 

 acid, which is much superior to calcium chloride. The effects 

 of moist air may so be demonstrated by passing the air through 

 water bottles, and the effects of warm air by heating very thor- 

 oughly a piece of gas pipe over a flame and aspirating air through 

 it. In carrying on the various experiments a thermometer and 



Fig. 3. Method of demonstrating effects of various factors on transpiration. 



hygrometers may be placed under a bell-glass to indicate the 

 changes in the air. This apparatus may be used to demonstrate 

 the [effects of chloroform, ether, illuminating gas, etc. on trans- 

 piration, and by the use of a simple mechanism the effects of 

 movements or vibrations on the plant in the bell-glass may be 

 determined, and in short, this apparatus may be used to demon- 

 strate most of the fundamental factors underlying transpiration. 



