Development of Laminaria hulbosa, L amour. 61 
paratively ignored. And yet the plant was well described at 
the beginning of last century, and the development of its bulb 
appears to have been known at the commencement of the pre- 
sent century. The first, and in some respects, best description 
is that of Reaumur in 1712. The most useful general account 
appears in Turner’s works, 1803-11 : while the most accurate 
description of the development of the bulb was given by Agardh 
in 1848. The position of the sporangia, long unknown, was 
first discovered by Sowerby on the furbelows in 1807: while 
not until 1885 was their presence on the bulb demonstrated. 
In the stalk there are five regions : 1. The primary fixing 
organ; 3. the bulb ; 3. a flattened twisted portion ; 4. a portion 
with flounced edges ; 5. a flat straight piece which passes up- 
wards into the lamina. 
It is difficult to make dogmatic statements as to the absolute 
significance of these parts. There can, however, be little doubt 
that the bulb has principally to do with fixing the plant to the 
sea-bottom. Its great increase in size and the development of 
successive circles of hapteres can only point to this conclusion. 
It is of further use, however, in forming a lodgment for spor- 
angia : and probably, where not forming sporangia, the epider- 
mal cells assimilate. So that if all the rest of the plant be torn 
away, as frequently happens in storms, there is still left in the 
bulb the possibility of assimilation and reproduction. The 
twisting of the stalk above the bulb causes it at this point 
to approach the form of a hollow cylinder — an arrangement 
obviously conferring a great increase of rigidity on this part. 
The greatly expanded part with convoluted edges, above 
the twist, appears to have a twofold function : firstly, it bears 
sporangia, and secondly, the arrangement of the edges in folds 
must add strength and rigidity. 
A similar explanation is given of the foldings in the stem of Caulotretus hetero- 
phyllus described by Warburg ; but in the latter case the median part is convoluted 
and the edges are perfectly flat. Caulotretus is a liana allied to Bauhinia ; and 
Haberlandt suggests the very natural explanation that the plant, by this peculiarity 
of the stem, acquires sufficient rigidity to enable it to reach branches to which 
it may become attached *. 
1 Physiolog. Pflanzenanatomie, p. 383. 
