EDITORS PREFACE. VI 1 



played, than in the arrangements, imperfectly known 

 as they hitherto are, by which life is maintained. 



In connection with the Author's remarks on the 

 effects of evaporation in plants, and the conse- 

 quences of its suppression, and with his opinions as 

 to the origin of the potato disease, I beg to refer the 

 reader to the Appendix for a very ingenious and ap- 

 parently well-founded plan for the protection of the 

 potato-plant against the terrible scourge under which 

 it has lately suffered. The views of Dr. Klotzsch, 

 the author of this plan, as to the nature of the 

 disease, coincide remarkably with those of Baron 

 Liebig, as explained in the present work. 



WILLIAM GREGORY. 



EDINBURGH, 3rd March, 1848. 



