32 
Busk on Volvox glohator. 
still it is much to be regretted that these modern lights, clear 
as they are, have not apparently been allowed to penetrate 
his mind, and that one to whom science is so much and so 
deeply indebted should retain views long since deservedly 
exploded by nearly all competent observers. 
The more common and best known form of Volvox glohator^ 
to the naked eye, or under a low power, appears as a trans- 
parent sphere, the surface of which is studded with numerous, 
regularly placed green granules or particles, and which con- 
tains in the interior several green globules, of various sizes in 
different individuals, though nearly always of uniform size in 
one and the same parent globe. 
These internal globes, which are the young or embryo 
Volvox^ at first adhere to the wall of the parent cell, although 
the precise mode of connexion is not very apparent. When 
thus affixed, they are in a different concentric plane to the 
smaller green granules. At a later period, and after they have 
attained a certain degree of development, these internal globes 
become detached, and frequently exhibit a rotatory motion, 
similar to that of the parent globe. 
In the form of Volvox^ termed V. aureus by Ehrenberg, 
the outer sphere, or cell, exhibits precisely the same structure 
as the above, the only apparent difference between them con- 
sisting in the deeper green colour of the internal globules. 
These, however, soon exhibit a more important distinctive 
character in the formation of a distinct cell-wall of consider- 
able thickness around the dark green globular mass. This 
wall becomes more and more distinct ; and, after a time, the 
contents, from dark green, change into a deep orange-yellow ; 
and simultaneously with this change of colour the wall of the 
globule acquires increased thickness, and appears double. 
The third form, or Volvox stellatus, differs in no respect 
from the two former, except in the form of the internal 
globules, which exhibit a stellate aspect, caused by the pro- 
jection on their surface of numerous conical eminences, formed 
of the hyaline substance, of which the outer wall of the 
globule is constituted. The deep green colour of the contents 
of these stellate embrj^os, and their subsequent changes into an 
orange colour, at once point out their close analogy with those 
of V. aureus. I have no doubt of their being merely modi- 
fications of the latter ; and, in fact, the two forms are very 
frequently to be met with intermixed, and on several occasions 
I have observed smooth and stellate globules in the interior of 
one and the same parent globe. 
The organism described and figured by Ehrenberg, under 
the name of SphcErosira volvox^ also presents the appearance 
