154 The Plant World 



thor should enunciate clearly the exact meaning he gives to his 

 terminology. 



The nomenclature of geographical and topographical units 

 and also of biological units is considered, the views of various 

 well known botanists are reported at length, and a certain num- 

 ber of definite propositions are presented to the Congress. The 

 citation of works of upwards of 160 different authors, "which 

 contain an expression of new points of view in regard to phyto- 

 geographical methods," adds to the value of the report and 

 shows very impressively something of the remarkable develop- 

 ment of the branch of science for which it is sought to open the 

 way to the attainment of a usable and stable nomenclature. 



