INTRODUCTION. XIX 



amongst the first to take the subject up, and that 

 though they did so under far more favorable circum- 

 stances than their predecessors did, yet that even 

 then the science of organic chemistry was in many 

 respects very imperfect and incomplete. 



During the last forty years, many important 

 additions have been made to this department of 

 Chemistry; improved and more accurate modes of 

 chemical investigation have enabled more exact ana- 

 lyses to be made of the different varieties of organic 

 matter; the composition of those substances which 

 constitute the bodies of animals and plants has been 

 accurately and carefully ascertained. At the same 

 time, many valuable observations have been made 

 respecting the functions of plants, the conditions 

 requisite to germination, the formation of flowers 

 and seed, the chemical changes attendant on the 

 ripening of fruit, the office performed by roots and 

 leaves, and a variety of other important subjects 

 of inquiry. The names of Liebig, Schiibler, and 

 Sprengel, in Germany; Braconnot, Boussingault, 

 Chevreul, Colin, Chaptal, Dumas, Edwards, and 

 Payen, in France ; and of Daubeny, Fownes, John- 

 ston, Pepys, Turner, Christison, and Way, in our 

 own country, deserve especial mention. 



Even in so short a sketch of the subject as this, it 



