Development of Laminaria bulbosa , Lam our. 63 
have over-exerted itself in this respect, and in spite of all its 
attempts does not escape being torn up bodily and cast on the 
shore. 
The facts just mentioned seem to indicate that L. bulbosa is 
an advanced type with a great amount of differentiation, and 
complicated attempts at adaptation. There does not seem to 
be a corresponding amount of histological differentiation. In 
fact, in this respect, it appears to possess a much simpler 
structure than allied species. Unfortunately I have not suc- 
ceeded in examining older specimens, and the appearance of 
complexity in the tissue frequently takes place comparatively 
late in other Laminarias. In the first place, I have not met 
with any zones of secondary thickening. This occurs in the 
stalks of other Laminarias and may be absent in L. bulbosa 
because of the flatness of this organ. At the same time the 
hapteres of L. saccharina and L. digitata increase in thickness 
in this manner, and I find nothing of the kind in the hapteres 
of L. bidbosa. Then, again, I have not met with any appear- 
ance of the mucilage-ducts found in various other Laminarias ; 
and the development of the trumpet-hyphae does not appear 
to be at all well marked. Finally, the presence of huge cells 
with many nuclei is certainly characteristic of the species, since 
this is largely prevented in other Laminarias by the appearance 
of zones of secondary meristem. This character, and the con- 
sequent increase in size of many parts by the increase in size of 
individual cells, rather than the multiplication of cells, seem to 
point to a low stage of histological differentiation. 
I have to record my thanks to Mr. Walter Gardiner for the 
material which I have examined, and for his assistance in 
arranging the subject-matter of this paper, and also for many 
valuable suggestions during its preparation. 
Botanical Laboratory, Cambridge, 
September 1888 . 
