EXPERIMENTAL PLANT PHYSIOLOGY. 



INTRODUCTION. 



A PLANT is a living organism which carries on, more or 

 less constantly, certain life-processes. The more important 

 of these are absorption of food-material* photosynthesis, respira- 

 tion, transpiration, secretion, and reproduction. The manner 

 in which these processes are performed is largely determined 

 by the influence of the external conditions of gravity, light, 

 heat, moisture, air, climate, etc. 



In order to obtain an insight into plant life it is necessary 

 to consider the nature, purpose, and mutual interaction of the 

 life-processes involved and to analyze the influence exerted 

 upon them by environment. 



The course of experiments detailed in this manual deals 

 only with the more salient features of plant physiology, and 

 is illustrative rather than quantitative. In some instances, 

 however, the simple treatment given may with proper applica- 

 tion yield exact results. The physical and chemical apparatus 

 possessed by every college or high school will be found suf- 

 ficient to carry out the work. 



Good plant-material is absolutely essential to the profit- 

 able performance of the experiments ; and unless a greenhouse 

 is at hand, the course should be pursued at a time when plants 

 may be grown in the open air. 



