PREFACE 



TO 



THE SECOND EDITION, 



THE first edition of this work being exhausted, I have taken the opportunity of in- 

 serting in this an abstract of the recent experiments and discoveries on the movements 

 of plants under the influence of light. It is chiefly derived from the report of a com- 

 mittee of the French Academy, published in June last. I have also corrected several 

 errors which were overlooked in the former edition, and made some improvements in 

 the general arrangement and appearance of the work. 



The favourable reception which this book has met with from the philosophical 

 world and the public, assures me that I was not mistaken in the estimate I placed upon 

 the importance of the subject on which it treats. The agency of the imponderables 

 in determining the production of chemical results, and more especially those connected 

 with the growth of plants, is beginning to obtain the attention of philosophers, and 

 doubtless before long will constitute a separate science. If any of the various problems 

 discussed in this book should facilitate the researches of others in this interesting and 

 beautiful department of knowledge, it will be to me a full reward for the labour and 

 time I have expended. 



JOHN W. DRAPER. 



April 28th, 1845. 



