779 FREE CELL-FORMATION. 
material. This latter may have very various appearances, whilst 
germinal matter is always the same. 
In vegetable tissues the formed material may be thick or 
thin, but has in every case been produced by germinal matter. 
Nutrition is effected by the constant passage of nutrient matters 
from without inwards through the formed material to the ger- 
minal matter, whilst the direction of growth is usually from 
within outwards, the new formed material being generally in- 
terior to that of longer existence. 
Cells originate in one of two ways: either free in the cavities 
of older cells, or at least in the protoplasmic fluid elaborated by 
their agency; or by the division of such cells. The first is 
called Free Cell-formation or Original Cell-formation ; the second, 
Cell-division or Cell-multiplication, which is the usual mode of 
growth in the nutritive organs of plants. 
A. FREE CELL-FORMATION.—We may distinguish two modi- 
fications of free cell-formation. 1. Free cell-formation from a 
nucleus or cytoblast ; and, 2. Free cell-formation without the 
previous formation of a nucleus. 
a. Free Cell-formation from a nucleus.—This mode was dis- 
covered by Schleiden, who at first considered it to be the 
only process of cell-formation that occurred in plants. Subse- 
quently he modified his views materially, not only as regarded 
the manner in which it took place, but also as to its universality, 
and admitted that it was only one principal mode of cell-forma- 
tion. The manner in which he describes it as taking place is as 
follows (jigs. 1128 and 1129) :—A portion of the protoplasm 
collects into a more or less rounded or somewhat oval form, with 
a defined outer border, thus forming the nucleus of the cell ; 
upon this a layer of protoplasm is deposited, which assumes the 
form of a membrane, and expands so as to form a vesicle ; on 
the outside of this a cellulose membrane is secreted, and the 
formation of the cell is completed. The protoplasmic vesicle 
in this case forms the subsequent lining of the young cell-walls, 
and constitutes the ‘primordial utricle’ of Mohl. 
b. Free Cell-formation without a previous nucleus.—In the 
process of free cell-formation, as described above, we have 
alluded to the production of the nucleus as the first step of 
the process, and it is regarded to be so in most instances by the 
greater number of observers. Henfrey, agreeing with Nageli 
&c., however, does not consider the nucleus of any physiological 
import in free cell-formation, which process he thus describes : 
—‘ The essential character of free cell-formation lies in the cir- 
cumstance that the protoplasm which produces the primary 
cellulose wall of the new cell previously becomes separated from 
the wall of the parent cell, so that the new cell is free (or loose) 
in the cavity of the parent cell.’ In some cases, it is certain, 
no nucleus can be detected in a cell previous to the formation 
of other cells free in its cavity; hence the presence of the 
