INTRODUCTION. 11 



zoology in view. M. Agassiz likewise ; and lie had notj be- 

 sideSj to deal witli species. Lindleyj and especially De Can- 

 dolle, are very explicit, considering the period when they 

 wrote j but many questions have arisen since then. Every 

 author is necessarily led by certain tendencies, by certain 

 exigencies of the times in which he lives ; whence it follows 

 that it is useful — every twenty years, for instance — to revise 

 the ensemble of received rules. Advantage is taken of this 

 revision to abandon useless rules, and to replace them by 

 more suitable ones. Without going far back, it is easy to 

 see that, since the end of the eighteenth century, botanists 

 have endeavoured to free themselves from many useless 

 shackles put on by Linnaeus, and tightened by his disciples ; 

 above aU, with relation to the choice of generic names. De 

 CandoUe was ruled by the idea of having the law of priority 

 properly respected, — a law which, fifty years ago, was often 

 unscrupulously infringed. Authors next aimed at greater 

 precision, and at making nomenclature answer to the grow- 

 ing necessity of dividing the vegetable kingdom iato more 

 numerous groups, comprehended one within another. 



In the present day, the nomenclature of cultivated species, 

 and of their innumerable modifications, requires special at- 

 tention. I do not propose any serious innovations in this 

 respect, only recommending botanists to choose, among the 

 various courses in use, those which seem most appropriate, 

 and to establish as close a correspondence as possible be- 



moat important of Linnseus' ideas, was, for a long time, deemed by him to 

 be of secondary importance ; and thus it is that, in the difierent editions 

 of the ' Philosophia,' all anterior to 1745, he expatiates on the phrase 

 nomina speciflca, and only mentions what we, to-day, call specific 

 names (his nomina trwialia). Among the 186 dissertations of Linnsens, 

 there is not a single one on the names now termed specific. In his disser- 

 tation of June, 1753, ' Incrementa Botanices ' (Amoen. Acad. iii. p. 377), 

 where he takes the title of reformer of science, and where his works, 

 even the ' Species ' that had just appeared, are referred to, he does not 

 advert to the use ofthe binominal nomenclature. He speaks of it, at last, 

 in his dissertation, ' Eeformatio Botanices ' (Amoen. Acad. vi. p. 315), 

 in December, 1762, but not to lay down any rules for these names, and 

 merely to insist on the very great advantages oflFered by them. 



