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uppermost in his thoughts during forty years of his life, during which 

 period he published twelve treatises on the subject. The result has 

 been the general acceptance of the principles he laid down, and the 

 adoption of the rules, except where expediency or exceptional condi- 

 tions clearly require their modification or supersession. 



Turning from A. de Candolle's taxonomic labours, it is on his 

 ' Geographic Botanique Raisonnee,' published in 1858, that his most 

 enduring claim, as a philosophical botanist, rests. The subject had 

 early attracted his attention. He was drawn to it both by inclina- 

 tion and by his father's admirable ' Essai Elementaire de Geographie 

 Botanique ' (published in 1820). An interesting chapter in his own 

 monograph on Gampanulacece (his earliest systematic work) is devoted 

 to it ; a more important one is embodied in his ' Introduction a 

 1'Etude de la Botaniqae ' (1835) ; and in 1848 he published 

 (' Comptes Rendus ') a suggestive essay on the northern limitation 

 of plants, adopting as a leading principle the " Methode des Sommes 

 de Temperature," as laid down by Boussingault in his " Economie 

 Rurale." 



It is impossible in a notice like the present to give even a general 

 review of the contents of a work covering such a wide range of in- 

 teresting and important considerations as the ' Geographie Botanique 

 Raisonnee,' and which enters into so many of these in extraordinary 

 detail. The impressions left in the mind after a first perusal are of 

 surprise at the astonishing number of the valuable observations 

 collected and collated from apparently inexhaustible sources, the 

 precision and methodical subdivision of the subject matter, and the 

 scrupulous care with which the labours of every previous author 

 and reasoner are treated. It may truly be said of the author of the 

 ' Geographie Botanique,' as has been of Darwin's ' Origin of Species/ 

 that he has utilised to the best purpose the waste and the rejected 

 observations of scores of less sagacious reasoners. Throughout the 

 work the search for general principles and laws is conspicuous. ISTo 

 methods known to him are left untried, the statistical above all others, 

 and even when these all fail, the materials left for the analysis of 

 future thinkers are so well knit together and so absolutely trust- 

 worthy that they have in numberless instances proved of great value. 

 The most conspicuous instance of this is to be found in the exhaustive 

 chapters devoted to the influences of heat and light on the 

 development of individuals and of species, and on the distribution of 

 the higher groups of plants. Though not always leading directly to 

 a precise correlation of cause with effect in the desired direction, the 

 value of these researches appears in another chapter, where it is 

 shown by a reference to them that the limitation of species, whether 

 on plains or mountains, is determined by the amount of heat above 

 the freezing point of water, that is absorbed during the months 



