M. WICHURA ON THE WINDING OF LEAVES. 277 



sition in the dimensions of breadth, right and left. But botanists 

 are not agreed which of the two opposite helices shall be called 

 a right- and which a left-wound helix. According to Linnaeus, 

 the Bean winds to the right and the Hop to the left. This 

 definition is arrived at in standing outside the winding, and in 

 tracing the latter from below upwards with the face turned 

 towards it. In this way both the observer and the twining stem 

 examined retain their natural positions. DeCandolle proposed 

 an opposite method. In defining the direction of the winding, 

 he placed himself in the central point, and, on the contrary, 

 called the Hop right- and the Bean left- wound. Most modern 

 authors have followed him, because, as they say, " in every in- 

 dependent object, right and left can only be determined accord- 

 ing to itself, from its own above and below, front and back." 



34. 



The correctness of this reason, however, and the preference 

 herein claimed for the newer terminology, cannot be admitted. 

 According to Kant* the right or left nature of the winding of a 

 spiral is a distinction " which is indeed given in perception, but 

 cannot by any means be clearly conceived, and thus cannot be 

 made comprehensible/' We do indeed see, when we hold two 

 oppositely wound helices against each other, that they represent 

 a perfect contrast in their relations to space, and in this way we 

 acquire a conception. But the examination of either singly will 

 not carry us to the same result. All that we attain is a percep- 

 tion in regard to space, and thus terminology would have fully 

 gained its object, if it succeeded in reproducing in us the im- 

 pression of the direction in space of any helix. Both DeCandolle's 

 and Linnaeus' s methods fulfil this, but neither of these does any 

 more. I have therefore returned to the terminology of Linnaeus, 

 since it is not only the older, but also has the preference over 

 that of DeCandolle on account of greater convenience in use. 



35. 



Another remark which I have to make on terminology refers 

 to the " aestivatio contorta." Linnaeus called flower-buds rolled 

 according to the diagram fig. 1. no. 2, right- wound, in which the 

 * Afelaphysitche Anfangsyriindc, 1787, p. 8. 



