278 PHYSIOLOGICAL BOTANY. 



which succeed each other in a continually alternating 

 direction in two series, separated by less than half the 

 circumference of the stem, are symmetrical, and the pro- 

 duct of forces uniform, but acting in opposite directions, 

 and this is the state of polarity. But all the buds and 

 leaves upon the stem grow upwards, and I cannot see how 

 polarity can act here. It always acts in directly opposite 

 directions, and not at angles. Important as it is to con- 

 sider an object not individually and separately, but as a 

 whole, there is no polarity manifested in this case, unless 

 we change the meaning of the word. The primary phe- 

 nomenon is ascent in the direction of a spiral, from a ver- 

 ticillate position. 



Morphological Communications, by WYDLER; on the 

 Characterization of Foliaceous Structures external to the 

 Flower. Bot. Zeit., 1844, p. 625. Wydler here treats 

 of some of Schimper's definitions of leaves. He divides 

 the leaves on a plant into inferior leaves (Niederblatter) , 

 frondose leaves (LaubUatter), and superior leaves (Hock- 

 blatter) ; again, each leaf into a vaginal portion, petiole, 

 and lamina. The frondose leaves consist of a, vaginal 

 leaves, consisting of the vaginal portions only, as in the 

 Iris ; b, petiolar leaves, consisting of a petiole only, as in 

 the Acacias, Indigofera juncea, and Lathyrus Aphaca ; 

 c, frondose leaves, consisting of vaginal portion and 

 petiole, as in Allium Cepa ; d, frondose leaves, consisting 

 of petiole and lamina, as in most plants ; e, laminar 

 leaves, consisting of the lamina only, as in sessile leaves ; 

 /, frondose leaves, consisting of vaginal portion, petiole, 

 and lamina, as in Arum, Palms, Rheum, the Urnbelliferse, 

 Leguminosae, and Rosacese. Many of these details are 

 applicable. The name vagina,, or sheath, is not inappro- 

 priate ; and by means of it, we can easily express the 

 distinction between an entire and a half sheath. Instead 

 of the word lamina, which is not German, we have plate, 

 leaf-plate (blade). The leaves of Iris do not consist 

 merely of a vagina, but of vagina and leaf-plate. Allium 



