M. WICHURA ON THE WINDING OF LEAVES. 311 



Mosses, is very considerable. Still larger is the number of the 

 plants with winding leaves enumerated in §§ 55-125. And it 

 must not be forgotten that, according to § 12?, there must be 

 movements of rotation which escape notice on account of their 

 slight degree ; as indeed, for example, the rotation of the indi- 

 vidual leaflets which causes the contorted aestivation is so slight, 

 that it would be wholly concealed were not its traces preserved 

 by the regular overlapping of the margins. In the face of such 

 considerations, the character of external fixedness, which it has 

 hitherto been customary to connect with the conception of a 

 plant, vanishes, and we rather arrive at the conviction that 

 plants, too, possess, in the rotation of the axis, a motion peculiar 

 to them, which reveals itself everywhere that the moving force 

 has not been already exhausted in latitudinal growth, and there 

 found a different expression proportionate to it. 



EXPLANATION OF PLATE IX. 



Figs. 1 & 2. Each of these figures represent horizontal sections of two penta- 

 [)hyllous buds rolled to opposite sides. 



Fig. 2. is intended to render clear the direction followed in the rotation. If 

 the line a 6 is to be removed, by a rotation round the point x, the 

 point of section of the axis of the leaf, into the situation marked by 

 the line c d, this takes place by a rotation which is continued to 

 things standing outside the rotation, as the arrows indicate, in No. 1. 

 from left to right, in No. 2. from right to left. The comparison of 

 the two figures 1 & 2, shows us that the aestivation fig. 1. No. 1. is 

 produced by the former movement, the aestivation fig. 1 . No. 2. by 

 the latter. Therefore, in logical application of the Linnsean termi- 

 nology of the aestivation, we call the arrangement fig. 1. No. 1. 

 right-wound, that of fig. 1. No. 2. left-wound. 



Fig. 3. Fruit oi Ailanthns glandulosa, L., wound to the right at the summit. 



Fig. 4. No. 1. Fruit of Erodium Cicutarium, L., on an enlarged scale. The 

 appendages of the carpels are wound to the left round the carpophore. 

 No. 2. A carpel separated from the carpophore, also magnified ; the 

 appendages wind to the right. 



Fig. 5. Leaf of an Avena, which is wound to the right below, and to the left 

 above. 



Fig. 6. Branch of Chrysocoma Linosyris, L. Leaves wound to the right in 

 agreement with the direction of the leaf-spiral. 



Fig. 7. Branch of Acacia micracantha, Desv. Phyllodia wound to the left in 

 correspondence with the direction of the leaf-spiral. 



Fig. 8. A left-wound and at the same time strongly curved leaf of Chrysanthus 

 angustifolia. 



Fig. 9. Branch of Dianthus trifasciatiis, W. & K., with left-wound leaves. 



[A. H.] 



