INTRODUCTION. y 



independent of tlie constant changes in known facts^ and 

 modes of viewing them. Botanists and horticulturists ex- 

 change jokes on the oddity of garden names, and on the in- 

 stability of a nomenclature which might well be deemed to 

 possess fixity, having been said to be positive and logical. 

 Happily, they likewise exchange polite and serious requests, 

 with a view of being useful, if possible, or at any rate not 

 hurtful, to one another. I have myself appealed to horticul- 

 turists^ not to give to simple cultivated varieties or sub- 

 varieties, Latin names, similar in form to those of genuine 

 species, in order to avoid a source of error in botanical 

 works ; while M. Charles Koch, taking advantage of the In- 

 ternational Botanical Congress, held in London, in 1866, 

 proposed that such meetings should be utilized for the ex- 

 amination of doubtful questions of nomenclature, and for 

 the introduction of such . reforms as should reduce syno- 

 nymy.2 



In London, we had only two meetings at our disposal, the 

 programmes of which were already very full ; besides which, 

 there was no text of propositions to form the basis of a dis- 

 cussion. We separated, in consequence, without having even 

 touched upon the subject. But the words of M. Koch were 

 not lost. He who had then the honour of presiding at the 

 sittings has frequently reflected on the matter since ; and 

 when he made known to the Committee for the Organiza- 

 tion of the Botanical Congress in Paris his desire specially 

 to treat questions relating to nomenclature, the Committee 

 engaged him to prepare a " code " of laws, so as to facilitate 

 the discussion of those points which might more particularly 

 engage the attention of the meeting. 



1 have attempted to comply with this desire. Long prac- 

 tice in systematic botany, continuous intercourse with many 

 able men who assist me in working out the ' Prodromus,' 

 and added to this, the valued recollection of the tendencies 

 imparted to me in my youth, made the, task more easy, per- 

 haps for me than for many others. The subject is so fami- 



• Bulletin du Congrfes hortioole a Bruxelles, 1864, p. 171. 



2 E/Oport of the Proceedings of the Botanical Congress, 1866, p. 188. 



