BOTANICAL NOMENCLATURE. 431 



however, that even the more strenuous of these reformers them- 

 selves admit certain exceptions. They have found it necessary, for 

 instance, to fix initial dates, and to rule out certain names as too 

 vague in their definition or too uncouth in their form to be 

 accepted." 



" Ideas as to the best mode of establishing rules or reaching 

 a general agreement regarding the necessary exceptions to the bald 

 principle of priority have differed widely and given rise to lively 

 controversy. To some it has seemed best to advise an ideal system 

 and then, without much reference to the wishes or convenience 

 of their colleagues, to apply it in local publication. To the vast 

 majority, however, it has been clear that the subject was a broad 

 one, involving much mutual sacrifice before the now divergent 

 usages at different botanical centers could be brought into har- 

 mony. The question is also an international one, requiring the 

 botanists of different nations to attain a common agreement. For 

 some years there was a growing desire for an international meet- 

 ing of representative botanists who should give the matter of 

 nomenclature careful consideration and come, if possible, to 

 some agreement on the fundamental rules to be followed. This 

 feeling took definite form in the year 1900, when preliminary 

 sessions of such a gathering were held in connection with the 

 Paris Congress of Botanists. At this meeting a bureau was 

 formed for the organization of an International Botanical- Con- 

 gress to be held at Vienna in June, 1905." This congress convened 

 in Vienna and was attended by between five and six hundred bota- 

 nists, representing the leading botanical institutions of the world. 

 They framed international rules which should be used in the 

 botanical nomenclature of vascular plants, and a complete list 

 of these will be found in Rhodora, the journal of the New 

 England Botanical Club, for March, 1907. A few of the general 

 considerations and leading principles will be mentioned, however, 

 in order that the student may have some understanding of the 

 subject. 



According to the Vienna Congress, the prescriptions, which 

 should govern the system of botanical nomenclature, are divided 

 into (i) principles, (2) rules, and (3) recommendations. 



Among the principles that should be adhered to is that scientific 



