284 ON THE GERM THEORY OF PUTREFACTION 
free from organisms by merely applying an efficient antiseptic as a preliminary 
measure to the meatus uvinarius ; and I have before referred to the high interest 
which attaches to this point. 
Secondly, it showed that if an organic liquid is obtained in an uncontami- 
nated state to begin with in a ‘ heated’ wine-glass, covered with a ‘ heated ’ 
cap shaped like an evaporating dish, and further protected by a glass shade, 
we are secure against the introduction of any organism from without, so long 
as the arrangement is left undisturbed. 
Further, the permanent freedom from contamination in this glass was 
particularly satisfactory, because, seven days after it was charged, I had re- 
moved a drachm of the liquid from it by means of a “ heated’ pipette, in order 
to ascertain the effect of water upon the unboiled urine as above alluded to 
(see p. 278). If no organic development resulted from the sudden entrance of 
so considerable a volume of air as then passed into the glass to take the place 
of the liquid withdrawn, it follows that, various as are the organisms which 
float in the atmosphere, they constitute but a very small proportion of the 
abounding particles of dust which a beam of sunlight reveals in an occupied 
apartment. 
A similar inference must be drawn from the circumstance before mentioned, 
that the sole result of forty minutes’ exposure of one of the glasses of this experi- 
ment to the air was the development of three plants of filamentous fungi, whereas 
the particles of dust which fell into it during that time must have been very 
much more numerous. 
If, then, the withdrawal of a drachm of liquid, or exposure for more than 
half an hour had so little effect, it was plain that the removal of one or two 
minims, executed nimbly so as to involve little more than momentary exposure, 
must be practicully free from the risk of accidental contamination. 
I thus became possessed of a means of making observations upon these 
minute but highly important organisms, which promised to yield results of a 
more definite character than any which had been hitherto obtained. 
Various detailed accounts have been given of late years, not only of the 
spontaneous generation of animal and vegetable forms of more or less com- 
plexity, such as large ciliated infusoria from an infusion of hay, or torulae and 
penicillia from milk globules, but also of the transition of one form of organism 
into another. But in the latter class, as in the former, the liability to deception 
is so extremely great, in consequence of microscopic organisms accidentally 
present developing side by side with the minute objects investigated, and pre- 
senting the appearance of growing out of them, that, without the slightest 
doubt being thrown upon the good faith of the observers, the so-called facts are 
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