CARPOSPOREM. 
From the carpospore of the fruit of Chara^ the sexual leaf-forming plant is not 
immediately developed, but a Pro-embryo precedes it, which attains only small dimen- 
sions and consists of a single row of cells with limited apical growth. The stem of 
the Leaf-bearing Sexual Plant springs from a cell which lies at some distance from 
the apex of the pro-embryo and grows in a direction nearly at right angles to that of 
its axis. The unlimited apical growth of the plant depends on an apical cell (Fig. 192, 
C, t) from which segments are cut off by transverse septa. Each segment immediately 
divides again by a transverse septum into two superposed 
cells, the lower one of which {g) always grows without 
further division into a long internode (frequently 5 to 6 cm. 
in length); the upper one scarcely lengthens, but i-s first 
divided in half by a vertical wall, and each half then 
divides by further successive septa so as to form a whorl 
of peripheral cells {b). From the node thus constituted 
the leaves are developed, each from a peripheral cell, 
and the normal lateral branches, which always originate 
from the axil of the first or of the two first leaves of 
the whorl. The leaves of such a whorl, from 4 to 10 
in number, repeat in a modified manner the develop- 
ment of the stem, but their apical growth is limited : 
after the formation of a definite number of segments, 
the apical cell ceases to divide and grows into the 
terminal cell of the leaf which is usually pointed (Fig. 
192, A, b"). From these leaves lateral leaflets may arise in 
a similar manner to that in which the leaves themselves 
have been formed from the stem ; and the leaflets may 
again in turn produce others of a higher order. The 
successive whorls of a stem alternate, and in such a 
manner that the oldest leaves of the whorl, in the axils 
of which the branches stand, are arranged on a spiral 
line winding round the stem. Each internode also 
usually undergoes a subsequent torsion in the same 
direction. The lateral branches, of which in Char a one 
is always developed in the axil of the oldest, in Nitella 
one in the axil of each of the two oldest leaves of the 
whorl, repeat the primary stem in all respects (Fig. 
203). It has already been mentioned that the leaves 
undergo a segmentation similar to that of the stem; they 
also consist at first of very short internodes which are 
afterwards greatly elongated (Fig. 192, 5, -y), and are 
separated by inconspicuous transverse plates or nodes. 
From these the leaflets arise in whorls the members of 
which are formed in succession, but they are directly 
superposed one above another, and do not alternate 
hke the whorls of primary leaves (Fig. 193, C-E, ß). 
(the basal node), by which it is united with the stem-node, and so is each leaflet 
with its primary leaf. These basal nodes are the points of origin of the formation 
of the cortex which, in the genus Chara, covers the internodes of the stem, but 
FIG. 191. — Chara f7-agilis ; sp g-eniiinat- 
ing spore; i d q pi together form the pro- 
embryo (pi is segmented, which is not 
clearly indicated in the drawing) ; at d are 
the rhizoids w, iu' the so-called primary 
root ; g\.\\& first leaves (not a whorl) of the 
second generation or leaf-bearing plant 
(after Pringsheim, X about 4). 
Each leaf begins with a node 
^ This has not yet been observed in Nitella. [See De Bary, Zur Keimungsgeschichte der 
Charen, Bot. Zeitg. 1875. The carpospore is first divided by a wall at right angles to its long axis 
into a small upper and a large lower cell. The upper cell is then divided by a wall at right angles 
to the first into two equal cells : from one of these the pro-embryo is developed, from the other the 
* primary root.'] 
