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 y^^ to -^^ 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 dm 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 A^hich I am now making known, 

 and to lay down a scale 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 phaenomenon 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 Avith 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 

 Diet, des Sci. Naturelles, art. Zoophytes, also from experience pro- 

 nounces against the generatio ccquivoca 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." 



1 could plainly distinguish with a microscope magnifying nearly 800 

 times zoological monads or animal organisms, which were filled by 



