XVI 



defined species of the north temperate zone, and little more than indi- 

 cations of the existence of a Tast contingent of Oriental, Asiatic, and 

 Malayan groups of species, specimens of which were scattered 

 through various great herbaria of Europe. These last presented the 

 greatest difficulties, and as showing how successfully they were 

 treated, it is instructive to find that in Dr. King's very recent mag- 

 nificent illustrated work on the oaks of India and the Malay Islands, 

 and which is founded on materials immeasurably superior to what 

 Alphonse de Candolle had access to, and on double the number of 

 species, all but one-eighth of those described in the Prodromus are 

 found to have been satisfactorily established upon sound scientific 

 principles. 



Before concluding the subject of the Prodromus, it must be re- 

 corded that over and above the labour expended on his own contribu- 

 tions to it was that involved in the editorship of the 17 volumes, in 

 the collection of materials for his collaborators, in the correspondence 

 with the latter, and in the revision of their work in MS. and in the 

 press laborious and often irksome duties all scrupulously per- 

 formed. 



The knowledge and experience acquired during the progress of the 

 Prodromus led to an exposition, for the guidance of monographers, 

 of his views as to the right method of proceeding in describing 

 plants. Three treatises may be classed under this head. The first is a 

 paper published in 1862, and entitled " Etudes sur I'espece, a 1'occa- 

 sion d'une Revision de la familie des Cupuliferes." It is an interest- 

 ing and instructive study of the meaning and application of the term 

 species as employed by naturalists, its limits and those of its mem- 

 bers, in time and area, their origin, future, and modifications. For 

 such a study he suggests the term epiontology. 



The second is entitled "La Phytographie, ou Tart de decrire les 

 vegetaux considered sous differents points de vue," published in 1880. 

 Founded primarily on the principles so well laid down by Linnaeus, 

 this excellent work embodies the results of de Candolle's own long 

 experience and those of his predecessors and contemporaries, on the 

 methods that should be followed by biologists, whether botanists or 

 zoologists, in describing organised beings. In this work the good 

 effect of de Candolle's legal training is conspicuous, for the prin- 

 ciples which he would see adopted, besides being unexceptionable, are 

 laid down with judgment, precision, and moderation that leave 

 nothing to be desired. 



The third is his " Lois de la Nomenclature JBotanique," which ap- 

 peared in ] 867, and in which rules were given for selecting, amongst 

 conflicting claims and opinions, the name a genus or species should 

 bear, assuming that it had borne two or more. So impressed was 

 de Candolle with the importance of this subject, that it was always 



