The Morphology of Ruppia Maritima. 107 
with the stem and squeezed out of the coleorrhiza, producing the 
ruptured end of the latter. In this figure the coleorrhiza had attained 
approximately its maximum development. It then, with its enclosed 
root, appears to the naked eye as a small, smooth, blunt projection 
at the node. A photograph of a longitudinal section of this stage 
is shown in Text-fig. 24. 
In the course of its growth the young root breaks through the 
coleorrhiza, which then remains at its base as a collar-like structure 
(Pl. VIII, fig. 45; Text-fig. 21). 
An interesting incidental point in relation to the coleorrhiza, and 
one which indeed may be connected with its function, is the 
occurrence in its surface layer (when of 
more than one layer in thickness) of cells 
which are evidently secretion cells (Text- 
fig. 25). 
It will be seen from the above de- 
scription of the coleorrhiza in Ruppia that 
it is of entirely different nature from that 
to which Sachs (1875, 1. c.) alludes. It has 
an external origin, being the outgrowth of 
the epidermis (including part of the im- 
mediately subjacent region) of that part 
of the stem which is situated over 
developing root. 
Such a structure as this evidently falls 
into the category of cS correlative y growths. Teese Netcare 
Having no immediate organic connection from surface of coleorrhiza. 
with the root and yet taking its inception showing secretion cells. 
close on the development of that organ, cateass 
the nature of its growth is analogous, for example, to the correlative 
growth manifested in the development of fruit and fruit-covering 
after fertilization of the egg cell and during the development of 
the embryo. 
As to the function of the coleorrhiza in Ruppia, not much can be 
said with any certainty. Perhaps it acts as an organ of protection 
for the root until the latter attains some length. The facts that it 
occurs only in water plants, so far as known; and that also, borne 
on it, are abundant secretion cells, may point to a functional secretion 
of slime of some sort to protect the young root in the water. 
Goebel (1893, pp. 233-237) has noted this quite general production 
of slime and slime-producing organs in water plants and has ex- 
plained in some detail its beneficial effects. It has already been 
Trans. Conn. Acap., Vol. XIV. 8 DrcemsEr, 1908. 
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