DEDICATION. 



in the living body are exclusively dependent on their influence. 

 The diseases incident to the period of growth of man, contagion . 

 and contagious matters, have their analogues in many chemical 

 processes. The investigation of the chemical connexion subsist- 

 ing between those actions proceeding in the living body, and the 

 transformations presented by chemical compounds, has also been 

 a subject of my inquiries. A perfect exhaustion of this subject, 

 so highly important to medicine, cannot be expected without the 

 co-operation of physiologists. Hence I have merely brought 

 forward the purely chemical part of the inquiry, and hope tc 

 attract attention to the subject. 



Since the time of the immortal author of the " Agricultural 

 Chemistry," no chemist has occupied himself in studying the 

 applications of chemical principles to the growth of vegetables, 

 and to organic processes. I have endeavored to follow the path 

 marked out by Sir Humphry Davy, who based his conclusions 

 only on that which was capable of inquiry and proof. This is 

 the path of true philosophical inquiry, which promises to lead us 

 to truth — the proper object of our research. 



In presenting this Report to the British Association I feel 

 myself bound to convey my sincere thanks to Dr. Lyon Playfair, 

 of St. Andrew's, for the active assistance which has been afforded 

 me in its preparation by that intelligent young chemist during his 

 residence in Giessen. I cannot suppress the wish that he may 

 succeed in being as useful, by his profound and well-grounded 

 knowledge of chemistry, as his talents promise. 



JUSTUS LIEBIG. 

 Giessen, 

 September 1, 1840. 



