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Some Observations on the Structure and Development of 
VoLVOX GLOBATOR, aud its relations to other unicellular 
Plants. By Geo. Busk, Esq., F.R.S. (Read May 26, 1852.) 
Three forms, or, as they are commonly regarded, species of 
Volvox are described and figured in Ehrenberg's great work, 
and have been noticed by other observers. These are V.glo- 
hator^ V. aureus, and V. stellatus. A fourth very similar or- 
ganism has also been described under the name of Sphcerosira 
Volvox, 
As I regard the three first named of these at all events, 
merely as forms or phases of one and the same species, the 
following observations will apply in some respects to all of 
them. They have more particular reference, however, to the 
common form of V. globator^ which happens to be that most 
accessible to me. 
This beautiful and well known object, which was first 
noticed by Leeuwenhoek, received little satisfactory elucida- 
tion until it fell under the observation of Ehrenberg, whose 
account of its structure and notions respecting its nature have 
been adopted by most subsequent observers, and have been 
received with little opposition until very lately — in fact until 
the beginning of last year. At that time Professor William- 
son read a paper on the subject before the Manchester Lite- 
rary and Philosophical Society, which is published in the 9th 
volume of their Memoirs. 
Professor Williamson's observations have led him to con- 
clusions in many points opposed to those arrived at by 
Ehrenberg, and especially are they confirmatory of Siebold's 
original view of the vegetable nature of Volvox. With respect to 
some points of structure, however, concerning which Professor 
Williamson differs from the Prussian observer, I am inclined, 
from my own observations, to side with the latter, whose 
errors in the case of Volvox are not those of direct observa- 
tion ; but in this instance, as in very many others, it is obvious 
that Ehrenberg has allowed his imagination, working upon 
preconceived notions, to play the part of reason in the inter- 
pretation of correctly-observed phenomena ; he has thence, 
in the explanation of what he has seen correctly, fallen occa- 
sionally into great and important errors. Whilst it cannot 
be denied that the recent progress of knowledge with respect 
to the structure and nature of the lowest classes of organised 
beings, places an observer of the present day in a position so 
much more advantageous, that it is scarcely fair to institute a 
comparison between him and the great and laborious Prussian 
microscopist, at the time his principal works were written, 
VOL. I. d 
