M. Miiller on the Development of Chara. 325 
between it and the stem-bud is merely, that this can be elongated 
to infinity, whilst the growth of the bud of the branch is very limited. 
This limit is shown in the apex of a branch (figs. 12, 13), which 
no longer appears as a bud, but as a simple terminal cell. The 
explanation of this limited and unlimited development is to be 
sought for in the fact that the cytoblastema of the stem has to 
take a direct ascending course, whilst in the branches this is at 
first indirect, 7. e. dependent upon the stem, devious, and limited ' 
by the amount of nutritious fluid. Thus the more the organs 
are removed from the centre of the individual, so much the more 
simple must they become, since enough nutriment is not present 
for a higher development. We also see this in a greater degree 
in the formation of the shoots. This is effected by the stmple cy- 
lindrical expansion of the external cells which are deposited upon the 
central cell of the branch ; consequently exactly in the same manner 
as the branches were formed from the stem. The difference be- 
tween them is merely, that here the further formation ceases, so 
that we have no more to do with buds, but merely simple cells, 
exactly as at the apex of the branch. Hence both agree in not pos- 
sessing the property, like the other parts of the stem and branch, 
which lie nearer to the axis of the individual, of forming a cortical 
layer. At the most they can only produce a few cells (articula- 
tions) in their interior. 
The peculiarity of the branch, that its membranes rapidly be- 
come thickened, is opposed to another property of the axial bud. 
This always possesses closed branches, 7. e. rolled up over it, 
which are only subsequently separated from it when the indivi- 
dual whorls of branches separate from each other by fresh in- 
crease. New whorls of branches,z. e. the most recently formed, 
appear in their place and surround the delicate terminal bud. 
Thus they defend it from accidental injury, since the oldest always 
cover the youngest, until the latter have become sufficiently strong 
to be able to undertake the same office for the younger branches. 
Of course this function does not occur in the shoots; they are 
therefore protected by becoming rapidly thickened. 
If we now compare the formation of the branches and the stem 
in the germinating and the perfect plant, we find the following 
essential difference, that in the former these organs are formed by 
intercalary or intermediate growth, whilst in the perfect plant they 
are produced directly. In the germinating plant the whorls of 
branches follow the formation of the stem; in the latter the 
branches and stem go hand and hand in development. In the 
former there are at first always two cells where an internode is 
about to form; in the latter the whorls of branches mark the 
internodes from the very commencement. Hence the former, 
strictly speaking, are only accidental, the latter are essential. 
