129 
Notice of Book. 
to botanists. But, though the existence of phenomena of this kind 
has been recognised, it will be admitted that Dr. Krabbe is justified in 
saying that they have never yet been made the subject of accurate 
study. It is proposed to deal seriatim with the principal points of 
Dr. Krabbe’s work, leaving to the end the more general conclusions 
suggested by it. 
Having defined 4 sliding growth/ the author goes on to speak of 
the cases in which it is well known to occur, pointing out that the 
most obvious examples, such as those above described in the growth 
of fungal hyphae and laticiferous cells, are connected with the rami- 
fication of cells. He then calls attention to the fact that sliding 
growth, so far from being limited to cases of this kind, takes place 
wherever single cells of a tissue grow in such a manner that their 
original arrangement cannot be maintained. In all such instances 
there must be independent growth of the several elements of the 
tissue, resulting in certain definite displacements and changes in their 
form. These changes are not only remarkable in themselves, but are 
of interest in relation to the superficial growth of the cell-wall, and 
also from their influence on the characteristic structure of the various 
tissues. 
The author illustrates the importance of his subject by pointing 
out that cell-divisions by themselves only play a limited part in 
the differentiation of the tissues of the vascular plants. The most 
characteristic constituents of the vascular bundle, namely vessels and 
sieve-tubes as well as tracheides, and bast and libriform fibres, all owe 
their mature form to processes of sliding growth. It is further 
maintained that the differences in the structure of successive annual 
rings and of spring and autumn wood depend on differences in the 
individual growth of their cells. 
The striking statement is made that whole tissues may be formed 
by sliding growth, without any cell-divisions taking place ; the author 
here refers, not to the familiar case of laticiferous cells, but to the 
development of the xylem in the secondary bundles of Dracaena and 
its allies. To this important point we shall have to return. Dr. 
Krabbe further shows that with the proof of the general occurrence 
of 4 sliding growth ’ in the higher plants, the distinction between the 
so-called 4 true ’ and 4 false 9 tissues is obliterated. 
The above general considerations serve to define the position of the 
author, and to introduce his detailed work. 
K 
