568 EHRENBERG ON ORGANIC MOLECULES AND ATOMS. 
observed in nature, and surpasses by far that of insects, yet it does not 
by a vast deal reach that of the polygastrical infusoria. In Parame- 
cium Aurelia, which is about 5); of a lin. in size, and which I observed 
with certainty during several days of a long duration of life, I have 
seen within twenty-four hours, by simple horizontal division, the oc- 
tuple increase of one individual, which would allow the possibility of the 
double of that increase. As however these animals increase not only 
by separation but also by eggs, and secrete these eggs not singly but 
in masses, and besides in addition to these form buds, we have such a 
possible immense increase of a single individual in forty-eight hours, 
that we may leave off counting and speak of innumerability*. 
Who now under such circumstances can wonder if within the space of 
two or three days fluids swarm with suck animals ? Is it not more natural 
to wonder howitisthat often itdoes not happen?. Wenolongernow require 
a generatio equivoca to explain these phenomena; they belong to those 
within the reach of experience and observation; and where anything 
astonishing of this kind may occur, the observer must take great care 
that the fault of superficialness be not laid to him. If therefore I 
supposed in my first paper that the generatio equivoea of infusoria 
might still be ascribed to their eggs, it now appears to me from obser- 
vations on the development and increase of individuals, that the neces- 
sity of such an hypothesis, and even its probability, must vanish. I 
now indeed believe that the generatio primitiva may as an ever- 
existing subject of experience have undergone its mortal combat. Upon 
this subject however I cannot undertake to solve all the problematic 
points relative to it, of which there are many and important ones, par- 
ticularly in relation to geology, as they are generally subjective, and 
but rarely objective; but I wish here to urge the consideration of the 
indefinitely small, as a main position for all branches of natural history, 
from which perhaps at a subsequent period I may also develop my 
more special views. 
II. On Atoms and Molecules as subjects of experience. 
Atomic philosophers have of late years, partly by their ingenious 
theories for the explanation of the phenomena of light, and partly by 
their ingenious as well as fertile atomic calculations of the doctrine of 
porportions in chemistry, obtained an undeniable practical superiority 
over dynamists, how much greater soever the satisfaction and recom- 
pense of the latter may seem to themselves to be; and hence it has 
happened that in the doctrine of the smallest particles of bodies we 
* This rapidity and great capability of increase of the infusovia might also be 
worthy the attention of analysing chemists, as they might quickly produce a great 
influence on organic substances, namely on some colouring substances. Boiling 
heat, or a few drops of alcohol, precipitate the infusoria, and they may then be 
removed as slime with certainty by filtration. It is necessary to operate quickly. 
