246 CONTRIBUTIONS TO
sumed, which, when the cell is moistened with water, comes forth in form of an intestine (wie ein Darm hervortritt), and in swelling expands itself over the fibres, thus appearing to surround them ; this is the case in most Salviæ and Polemoniaceæ, in Senecio flaccidus, Ocymum polystachyum and polycladum (Lumnitzera, Jacq.) There is an intermediate form between this and the former, when the jelly itself forms a broad spirally-wound band, which appear upon its surface to be composed of innumerable delicate fibres; their occurrence in this state is very beautifully shown in Perdicium Taraxaci and Ziziphora. A still less advanced stage of development exhibits merely a cylinder or cone of gelatine in the interior of the cell, the surface of which, however, is marked with delicate spiral lines. This is seen in some Salviæ, in S. verticillata for example, and in Leptosiphon androsaceum. Finally, the lowest stage of development is where the gelatinous cylinder, which is furnished with spiral striæ, has a cavity in its interior containing starch, which has not as yet undergone decomposition; this instructive phenomenon is found in Dracocephalum moldavica, Ocymum basilicum, and some allied species. In illustration of the above, consult plate 2, figs. 1-10, with their explanations.
Before quitting the subject of spiral fibre, I will merely add, what indeed has been of late admitted by every good observer, that the only difference between spiral cell and spiral vessel consists in the dimensions, although constant transitions may be observed between them just as well as between the cells of the liber and the parenchyma; and consequently, as regards this doctrine at least, there is no longer any place for natural-philosophical phantasies about the arrestment of ideal forms of higher types, and such like empty words. That which forms a liber-cell out of a round cell, the preponderating expansion of an organ lengthwise, is also that which transforms the spiral cells (the vermiform bodies) into spiral vessels. The function of the spiral fibre, however, is, as every candid vegetable physiologist will certainly admit, entirely unknown to us at the present time. It is certain that spiral vessels and spiral cells occur in the living plant quite as frequently filled with sap (in the younger vegetating portions) as with air (in the older organs which have attained their full size); and it is this which has
