THE HIGHER CRYPTOGAMIA. 303 



leafy shoot, vascular bundles are formed in the interior of 

 the two organs : in the stem there are three arranged in a 

 narrow circle ; in the root one single axile bundle. In the 

 first node of the germ -plant, at the place where the first 

 leafy branch and the first adventitious root branch off from 

 the primary axis, all the cells into which the vascular 

 bundles of both unite, are transformed into short annular 

 and spiral cells, forming a closed ligneous mass without 

 pith (PI. XXXIX, fig. 6). The primary axis of the embryo, 

 which is far less developed in the Equisetaceas than in the 

 ferns and Rhizocarpeas, and which now stands at the side of 

 the germ-plant, remains devoid of vessels. Its cells, which 

 now contain much chlorophyll, become elongated upwards. 



When the first leafy branch has reached a certain stage 

 of development, an adventitious bud is produced in the in- 

 terior of its cortical tissue by the multiplication of a cambial 

 cell of its base, at the elevation of the solid ligneous 

 mass of the first node. This bud is situated on that side 

 of the leafy shoot which is turned away from the primary 

 axis of the germ plant and below the depression formed by 

 the two lobes of the first sheath (PI. XXXIX, fig. 6). In 

 its position as well as in its mode of development it corres- 

 ponds entirely with the adventitious buds, by which all the 

 ramification of the developed Equisetum is effected. It 

 grows rapidly and vigorously and breaks through the bark 

 of its mother-shoot into the open air. It is distinguished 

 from the first leafy axis by having sheathing leaves with 

 four teeth, and at first also by its pale yellow, ivory-like 

 colour. The new shoot, which is far more vigorously 

 developed than the first shoot, is the second link in the 

 series of shoots originating from the adventitious buds of 

 the lowest sheaths. It is by means of these latter shoots 

 that the vigorous shoots with many-toothed sheaths and more 

 ample ramifications are produced from the delicate primary 

 stem which bears leaves with three teeth. The basal ad- 

 ventitious buds of the above vigorous shoots at last become 

 fruit-bearing stems. 



Sometimes the third, and if not the third, one or more 

 of the subsequent principal adventitious buds (by which 

 the duration of the germ-plant is secured) assume in the 



