264 
Experiments on 
[Monthly Microscopical 
Journal, Nov. 1, 1869. 
form agrees very nearly with the genus Sphaerosira volvox, as 
figured by Pritchard (edit. 1842, t. i., Figs. 48, 49). The proto- 
plasm in which these animals were imbedded had a faint reticulated 
appearance, which would make it rank nearer the genus Volvox, 
and the animals could be seen waving and wriggling their tails 
between the meshes. Vibriones were at this time very abun- 
dant, and amongst them I observed a number of white, spherical, 
transparent bodies rolling through the fluid — just the kind of 
movement one sees in Volvox globator. These I believe to be 
Monas umhra, as they agree in size with that species, 2 ¥ioirth of 
an inch in diameter. 
Dr. Hughes Bennett says : " It frequently happens that, soon 
after some of these higher infusoria are seen, the pellicle falls to 
the bottom of the fluid, where it constitutes a dense precipitate, 
and slowly breaks down ; then another scum forms on the surface, 
and molecules, bacteria, and vibrios are again produced." 
" The varied forms produced are spoken of by Ehrenberg and 
other naturalists as being different species, but I think it will be 
found that the laws, not only of molecular, but of alternate genera- 
tion and parthenogenesis, prevail among them, and one frequently 
passes into another."* But a little farther on he says : — " In all 
cases no kind of animalcule or fungus is ever seen to originate from 
pre-existing cells or larger bodies, but always from molecules." 
The various forms as spoken of by Ehrenberg might, under 
certain conditions, constitute what we are pleased to call species ; 
but we have only seen them under one condition, and that one con- 
dition has revealed these forms very distinctly, as distinctly, in fact, 
as many so-called species, and, so far as we know of them, they seem 
equally entitled to rank as such. Could their existence be pro- 
longed, and could they be placed in more genial media, the pro- 
bability is that we might see them develop into other forms. In 
one instance I tried this by taking what M. Pouchet has described 
as the perfect ovum derived from the molecular mass. I placed it 
in a watch-glass half-filled with water, and covered with a bell- 
glass ; but, at the end of a fortnight, I could discover no permanent 
or particular development, only that the molecules had become 
slightly larger. But there is one thing to be observed here, the 
specimen might not have been placed in its proper medium, and it 
might not have been supplied with proper nourishment for its 
further development. It would therefore be wrong to say that this 
microcosm had reached its ultimate form. The great fact then is, 
that we can to a certain extent see the beginning, but we cannot at 
present see the end. 
On the 22nd day some curious and beautiful forms revealed 
themselves. I observed five of them in a group, varying in size. 
* ' Popular Science Be view/ pp. 55, 56. 1869. 
