CHAP, ii.] of Plants. De Candolle. 515 



to the general theory ; but this is a reason why we should take 

 a nearer look at them, that we may learn how the spirit and 

 tendencies of the time were reflected in vegetable physiology, 

 and made themselves felt particularly in the theory of nutrition. 

 De Candolle's work appeared in French in 1832 in two 

 volumes, the first only being devoted to the subject of the 

 nutrition of plants, and in German in 1833 with many valu- 

 able annotations by the translator Roeper, under the title, 

 ' Pflanzenphysiologie oder Darstellung der Lebenskrafte und 

 Lebensverrichtungen der Gewachse.' It suffers, in common 

 with the other two books we have mentioned on the same 

 subject, and with the earlier works of Du Hamel, Mustel, 

 and other writers, from a too discursive mode of treatment, 

 which has the effect of burying the points of fundamental 

 importance under a huge mass of facts and statements from 

 other writers. It contains much that might have been 

 omitted as obsolete, and much empirical material of a purely 

 chemical nature, which could not at that time be applied to 

 the purposes of physiology. Nevertheless, it deserved the 

 great consideration which it enjoyed for a long time, especi- 

 ally in Germany, for its author had undertaken to treat veget- 

 able physiology as a separate and peculiar branch of know- 

 ledge, not ignoring at the same time its connection with and 

 dependence on physics, chemistry, phytotomy, and biology 

 proper, and thus to give a full and complete delineation of 

 vegetable life ; whereas the best works that had been written 

 since Du Hamel's time, especially on the nutrition of plants, 

 had proceeded from chemists and physicists or from plant- 

 growers like Knight and Cotta, who treated the subject in a 

 one-sided manner, each from his own point of view, and made 

 no attempt to give a connected account of all the phenomena 

 of vegetation. For this reason De Candolle's 'Physiologic 

 vegetale' is the most important performance that appeared 

 after Du Hamel's 'Physique des Arbres'; and if we wish to 

 know what progress was made in vegetable physiology gener- 



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