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describing these objects from that point o£ view without think- 

 ing of any other, — so natural, as we shall see, that Linnseus 

 fell into it himself, and there remained. Yet, that the oppos- 

 ing view has also its fitness is obvious from the fact that the 

 physicists and mathematicians are divided in usage, no less 

 than the naturalists. 



In the actual state of the case, the question which view 

 ought to prevail in botany must be determined therefore on 

 a balance of considerations : 1, Priority and authority, such 

 as that of Linnseus ; 2, Naturalness ; 3, Preponderant actual 

 usage. We had maintained in this Journal (for March and 

 for May, 1877) and in " Structural Botany " (6th ed., note 

 on pp. 51, 52) that the externe visum view has decidedly the 

 best case on the second ground, and, except in botany, on the 

 third also. And now that De Candolle has drawn our atten- 

 tion to the matter, we are going to claim the remaining ground 

 likewise, and to contend that the contrary usage in botany 

 came in from non-attention to the teaching and practice of 

 Linnseus himself. 



On p. 39 of Linnaeus's only own edition of the " Philosophia 

 Botanica" he defines and illustrates the directions of twin- 

 ing thus : " Sinlstrorsum^ secundum solem vulgo : Humulus, 

 Helxine, Lonicera, Tamus. Dextrorsum^ contra motum solis 

 vulgi ; Convolvulus, Basella, Phaseolus, Cynanche, Euphor- 

 bia, Eupatorium." 



Nothing is said about the position of the observer. But 

 in every one of the examples of sinistrorse (Helxine being 

 Polygonum convolvulus)^ the stem winds around the support 

 passing from right to left of the observer confronting the coil ; 

 and in every one of the dextrorse examples (Eupatorium 

 being Mikania) it winds in the opposite direction. That is, 

 dextrorse and sinistrorse are used in the externe visum sense. 

 On p. 103 the same is repeated, except that reference to the 

 sun's apparent course is omitted and additional examples are 

 added, most (but not all) of them accordant with the preced- 

 ing. So far, it would seem that Wichura was not mistaken 

 in his statement that De Candolle had followed a different 

 method from that of Linnseus. And this appears to be the 

 whole case as respects direction of twining. 



