Williamson oh Volvox glohator. 
45 
planation of the hexagonal areolation, however, does not clash 
at all with that which I have given as to the structure of the 
wall of Volvox. For in this case, as in all others, the collected 
mass of zoospores, and their envelopes, is enclosed by a con- 
tinuous external membrane, not in any way derived from them 
but from the parent cell in which they were originally formed. 
There are several other interesting points relating to Volvox 
which have come under my observation in a prolonged atten- 
tion to the subject, including another form of development of 
the internal spore, in which it divides, not in the usual way, 
into what may perhaps not inappropriately be considered as 
macrogonidia, to use Braun's expression, but into a much 
smaller and differently arranged sort, which may be considered 
as his microgonidia ; but to enter fully upon this and other 
points would demand more space than is here at command. 
[Whilst this paper is passing through the press, I have 
found that a faint, but quite distinct, purplish blue tinge may 
be produced in the wall of Volvox glohator by means of 
Schultz's solution. The specimens of Volvox in which I 
have noticed this have been preserved in glycerine for two 
months. — G. B.] 
Further Elucidations of the Structure of Volvox globator. 
By Professor W. C. Williamson. (Read June 21, 1852.) 
In May, 1851, I had the honour of laying before the Philo- 
sophical Society of Manchester a memoir on the Volvox gloha- 
tor* containing the results of a series of observations, which 
brought to light in that elegant object, a cellular structure, 
hitherto unobserved. Since the existence of these cells affects 
the character and affinities of the organism, it is desirable 
that the fact should be established beyond the possibility of 
dispute. My friend Mr. Busk, in a recent communication 
made to the Microscopical Society of London, either doubts 
their existence, or rejects my idea of their cellular nature. 
This denial, coming from such a quarter, renders it incumbent 
upon me to make the matter more plain than was done in my 
previous memoir : I am enabled to do this, partly by new ob- 
servations on the living Volvox^ and partly by some changes 
which the specimens prepared last year have undergone, 
making their structure more obvious than it previously was. 
* Published in tlie Niuth Volume of its Transactions. 
