vi PKEFACE 



principles will do well to follow the lines laid down in this 

 treatise by Professor Sorauer, and to discuss the often very 

 direct bearing of the physiological truths upon the questions 

 which exercise the minds of gardeners and agriculturists. 

 For these the book is directly written, though other students 

 of botany will find much useful information in this treatise, 

 emphasis being laid by the writer upon the fundamental 

 truths by a repeated treatment of them under various aspects. 

 In conclusion, I would thank Dr. Maxwell T. Masters for 

 information on some of the technicalities of horticulture, 

 always given so freely and so kindly. 



F. B. WEISS. 



