34 
REPORT ON BOTANY, MDCCCXLl : 
developed in a higher degree, whilst others remain in their 
original simplicity. 3d, The same central point from whence 
a perfect development of the vascular bundles takes place in 
both directions, is the point also where the latter leave the 
stem, to the formation of which they contribute the essential 
part, 4th, Between the internal or the stem-part, and the 
external or the leaf-part, of the vascular bundles in the plant, 
there is an opposition, which, remarkable enough, never pro- 
duces an identical matter, but only that which is analagous, 
and in proportion to the distance from the central point. 5th, 
With regard to the nature of the elementary parts, or the origin 
of the vascular bundles, it appears that the proper vessels (vasa 
propria) form the first and most essential part of them (the 
author explains, that the proper vessels consist of thin walled 
cells, consequently they are very difierent things from those 
which are called so by other Botanists), not only in as much 
as they are the elementary parts which first of all appear, but 
also because they form the most permanent part of the tissues, 
and never entirely disappear among ail the metamorphoses of 
the vascular bundles, and consequently cannot be replaced by 
other tissues. I must leave it to others to search for proofs 
of the truth of these conclusions, 
IV. Comparison of the Development of the Vascular 
Bundles in different Monocotyledons. — In this part, the 
course of the vascular bundles in the palms, according to 
Mohl, and in the Aloinece (in which there is no ramification, 
as Mohl found in the palms), as Meneghini describes it, is 
adopted. The course and ramification of the vascular bundles 
in the Ananas^ and also their course and entangling in the 
grasses, are considered. 
V. On the Structure and the Development of the Dipera- 
cece . — We give the authors own words on this point. In all 
Piperacem there is a central system of vascular bundles, 
which may be distinguished from a peripheral system ; these 
two systems consist of parallel vascular bundles, which run 
through the stem, and nowhere anastomose with each other. 
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