Development of Laminaria bulbosa, L amour. 57 
one of the older hapteres they are filled with dense brown 
contents. In a longitudinal section they are seen to be of 
great size, and the whole haptere appears to be of a spongy 
consistence. There is no strand of tissue in the haptere at all 
comparable with the narrow elongated elements representing 
the transport tissue of other parts; and in this respect the 
resemblance to the true hapteres of Podostemaceae, described 
by Warming, is very striking. In both cases we have merely 
to do with the primary fixing function of roots, the secondary 
function of absorption does not come into play. 
The increase in size of the haptere seems to be due in very 
great measure to the distension of its cells. The epidermis 
remains comparatively inactive as long as the substratum is 
not reached. As soon, however, as the haptere touches the 
substratum, as for instance a piece of rock, the epidermal cells 
appear in a new light. Each cell grows out after the manner 
of a root-hair, often apparently while at some distance from 
the piece of rock : a cubical basal portion is cut off, and 
usually several transverse walls appear in its course (Fig. 21). 
The ends of these rhizoids become attached after the manner of 
root-hairs of Phanerogams to any particles on the surface of the 
rock. It is probable that such intimate contact is not accom- 
panied by the solution of the particles, but merely contributes 
to the firmness with which the plant adheres to the substratum. 
This activity of the epidermal cells on approaching the substratum is very unlike 
the condition described by Grabendorfer 1 for the fixing organs of Durvillaea 
and Lessonia. In Lessonia ovata the capacity for division leaves the epidermal 
cells the moment they touch the substratum ; and in Durvillaea they quickly 
become permanent and filled with dark contents. Those epidermal cells which 
are nearest the latter, but which are still free, undergo division, and are pressed 
in turn against the substratum by the increase in size of the part ; and thus 
a continually increasing surface is formed which, by pressing into all the un- 
evennesses of the rock, forms a firm attachment for the plant. This formation of 
root-hairs is not confined to L. bulbosa. Thus, numerous root-hairs are formed on 
the hapteres of Pycnophycus. In Alaria esculenta, on the under side of the 
rhizome-branches, the epidermal cells grow out in bunches or masses to unicellular 
root-hairs 2 . There are in this species, according to Reink e ; bunches of out- 
growing epidermal cells on the lamina as well. These hairs, however, whose 
1 Reinke, in Pringsh. Jahrb. x (1876). 
