Vegetable Physiology for the Year 1836. 71 



find in the structure of stems, &c. In order, however, to 

 complete their history, to determine their degree of similarity, 

 which was only indicated by Mohl, we must distinguish in 

 each stem the florescent part from the rest, which very fre- 

 quently is reduced to the smallest dimensions. By means of 

 this distinction only are we able to explain the structure of 

 the stem, which Mohl called tubular, because it is peculiar 

 to the palms of the genus Calamus^ which cannot be compared, 

 as regards the inner structure, with any other plant of that 

 family, except at its lower part, which serves as the common 

 axis, from whence these new germs proceed. 



Mohl has said nothing respecting the structure of the per- 

 ennial shoots, in which Mirbel thought he was able to observe 

 a double vegetation. In fact we must distinguish the fibrous 

 productions of the leaves in them from those of the buds. 

 Both are circumstanced similarly to the upper course of the 

 vascular bundles of all other monocotyledonous stems. At 

 the basis of the chief axes only of the root-stalk, and of the 

 secondary one at the angles of the leaves, are found the under 

 courses of these fibres, and the constant separation which 

 such courses invariably preserve opposed to the first. Then 

 only, when the leaves continue to surround the stem in its 

 entire circumference, or when they are rolled together in 

 more than one circle, and when at the same time the one is 

 brought to some distance from the other, can it happen that 

 the fibres at the insertion of the leaf become peripherical ; 

 although they are all inclined towards the same direction, as 

 in the Juncacece, Cyperacece, &c. This peculiarity is still more 

 evident in the culms, on account of the double spiral lines 

 which regulate the motions of the leaves. Moldenhawer had 

 already taught that the bundles of the older leaves pierced 

 deeper into the fibrous body of the culms ; but the structure 

 and the origin of the nodi remained hidden. Led by the 

 above observations, I succeeded by elucidating this case, which 

 is the most difficult of all, in giving a plainer explanation of 

 this principle, by which in the monocotyledons the displace- 

 ments of the external organs may be regarded as the cause of 

 the inner arrangement of the vascular fibres. 



One of the most influential works of last year is that of 

 Link *, in which he intends to publish a great series of phy- 

 totomical plates. In the preface to this work. Link says that 

 the anatomy of the human body has made great progress 

 since learned men have begun to cause drawings to be made 



* Tconcs anatomico-hotaniccB ad illuslranda clcmenla phUosop/iicc botanicce. 

 Fasc 1. cum Tabttlis lit/iographicis viii. Bcroiini 1837. fol. Latin and German. 



