128 
Notice of Book. 
development of the tissues of plants has long been known. For 
example, the so-called ‘ false tissues ’ of most Fungi and some Algae 
consist of felted masses of interwoven branched filaments arising 
from a small number of originally distinct hyphae. It is evident that 
during the growth of such tissues the constituent hyphae must con- 
stantly have to force their way between their neighbours, and that 
thus complicated processes of sliding growth are involved. 
A similar case is found in the development of laticiferous cells. 
These cells, as is well known, attain an enormous length, and send 
out branches into every part of the plant, so that the whole complex 
laticiferous system consists of the innumerable ramifications of a 
small number of undivided cells. The penetration of these branches 
into the various tissues of the plant necessitates the continual sliding 
growth of the laticiferous cells on the adjacent cells. As has often 
been pointed out, these organs behave quite like the hyphae of a 
parasitic fungus when making their way through the tissues of the 
host. 
Nor has the occurrence of sliding growth in the formation of other 
kinds of tissue been wholly overlooked. The definition of £ prosen- 
chyma/ for example, even in the older text-books, contains the 
statement that the end of the cells £ are insinuated into the spaces 
between those lying above and below them 1 / This implies a change 
in the relative position of the elements in question. 
In De Bary’s work on the Comparative Anatomy of the Phanero- 
gams and Ferns the occurrence of mutual displacements of cells 
during their development is explicitly mentioned in various cases. 
Thus, at p. 462 (English edition) the possibility of such displace- 
ments during the formation of irregular groups of sieve-tubes is 
recognised; and at p. 470 it is stated that the fibrous elements of the 
wood £ show a great elongation on transition from the cambial 
condition to that of mature tissue, in the course of which they insert 
their tapering ends, which are the principal seat of growth, between 
each other/ Displacements in the transverse direction, due to the 
growth of large vessels, are also referred to, p. 470. 
It would be easy to cite many other passages from the various 
works on the anatomy of plants, showing that some of the changes 
comprehended under the term £ sliding growth’ have long been known 
1 Henfrey, Elementary Course of Botany, 2nd edition, 1870, p. 501. 
