572 EHRENBERG ON ORGANIC MOLECULES AND ATOMS, 
after the manner of the earlier philosophers, and in truth not very 
profound, on the nature of the organic bodies in infusions; and he ima- 
gines he has arrived at this result, that a transition takes place from 
vegetable to animal life, and vice versa. (Isis, 1831, p. 1083.) 
The examples mentioned in manuals of physics of the great divisi- 
bility and ductility of different bodies are for the most part small 
magnitudes merely in appearance. A gold leaf, thin as it may 
appear, is about 7555 tO apna of a line in thickness. 
It has not here been my intention to give a collection of the opinions 
of natural philosophers and chemists respecting atoms, but to call to 
memory only a few of those statements as to which I am best informed 
and most certain, of the magnitudes of the smallest particles of bodies 
which have been observed and calculated, in order to add to them the 
results of more recent observations which I am now making known, 
and to lay down a seale for them. The most recent theoretical state- 
ments do not give any very great degree of minuteness to the ultimate 
particles of bodies; the observations of Mr. R. Brown very nearly ap- 
proximate to those statements. 
The common opinion that infusoria or mould could be made by 
pouring water on dead organic matter I must pronounce to be com- 
pletely contradicted by the whole series of my observations. It is true 
the phenomenon is very deceptive; but if we observe carefully, there 
appear, even with the very same treatment, at one time some kinds of 
infusorial forms, and at another time others; and I have never had it 
in my power to produce certain forms with certain infusions, although 
this is found stated in all manuals as true, and succeeded (by their own 
account) with all earlier observers. There are however, according to 
the results which I have obtained, certain common forms, which are 
most generally diffused, the eggs or individuals of which may be present 
in all liquids, even in some, perhaps only the noxious, parts of plants, 
and of which at times the one form, at times another, may rapidly 
increase according to the eggs or single individuals which were present 
in the water, or had been introduced into it. M. Blainville in the 
Dict. des Sci. Naturelles, art. ZoopuHyTEs, also from experience pro- 
nounces against the generatio @quivoca in infusions: “I have often 
taken great pains without any success to produce any kind of organic 
body in small glasses by spontaneous development, although other 
glasses by its side containing the same water were soon filled with them. 
Besides the discovery of this error respecting infusorial fermentation, 
which not only proves false in fact, as is also manifest from the de- 
velopment of the forms, my investigations respecting the minutest 
organic particles have led me to recognise the following minute mag- 
nitudes as really existing and perceptible to the senses.” 
I could plainly distinguish with a microscope magnifying nearly 800 
times zoological monads or animal organisms, which were filled by 
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