328 L- A. GIDDINGS 



CONCLUSION 



From the foregoing experiments it seems evident that there 

 exists a very close relationship between transpiration and evap- 

 oration. The same agents that are active and efficient in evap- 

 oration are also active in transpiration, but in transpiration 

 there are evidently other factors than those concerned in evap- 

 oration. The plant itself apparently has the power of influenc- 

 ing transpiration to a certain extent. It seems to be able to 

 exercise a regulative influence whereby it can check transpiration 

 even though the rate of evaporation continues to increase. Out- 

 side of the plant itself, the chief agents concerned in transpiration 

 are wind velocity, temperature, and relative humidity. Trans- 

 spiration, up to a certain point, increases with increased wind 

 velocity, increased temperature, and decreased relative humidity. 

 In this respect it agrees very well with evaporation, but evapor- 

 ation is entirely dependent upon outside factors. Transpiration 

 seems rather to be governed by the activity of the plant which 

 may be influenced largely by external factors, but does not 

 correspond throughout with the fluctuations produced by the 

 agents of evaporation. Transpiration and evaporation are not 

 entirely the same thing though more or less related. 



