NOTES OF ALGÆ,. 377 
bending of the filament upon itself, presenting the ap- 
pearance of a writhing motion ; third, the progressive gliding 
motion of an entire filament or of a fragment, resembling 
that of certain Mollusca or Planariee. 
Mr. P. Grant has directed my attention to a remarkable 
motion, which may be observed in newly collected specimens 
of Hematococcus binalis. This beautiful species propagates 
freely by self-division ; and the cells vary in number in 
different individuals > in some 2 and 4, in others 8, and 
more rarely 16. The phenomenon in question is that of 
rotation of the cells in the interior of the mucous matter 
Which surrounds them. Leuwenhoeck observed long ago 
that, in the ova, of certain Mollusca, the yolk revolves in the 
surrounding fluid, at a certain stage. If there be no mistake 
; about the phenomenon alluded to in Hematococcus, and I 
cannot detect any source of deception, and if to it, we add 
the mode of subdivision of the cells, we have a remarkable 
analogy between the ovum of certain animals, and an or- 
ganism decidedly vegetable, and of very simple structure. 
In the ovum of the animal it is well known that the motion 
18 produced by ciliæ, which make their appearance af an 
advanced stage ; what may be the true cause in the plant I 
- unable at present to say.* — dae aie dee 
The Diatomacee here enumerated must not be considered eee 
55 presenting a complete view of the species occurring at the — 
altitudes alluded to; for the present, the more common 
forms are alone mentioned. Respecting their right to a 
Place in the vegetable kingdom no doubt can remain, after 
the recent very important discovery of Mr. Thwaites; that 
zealous and accurate observer having detected a species of 
Eunotia in conjugation, as well as Gomphonema minutissimum. — 
pecting one genus, viz. Schizonema, it may not be irrele- 
vant to state, that the frustules seem to be developed from 
cells, propagating by self-division as well. The very ger 
* The motion in the Hematococcus is very slow, compared with that 
