118 WYMAN, ON THE FORMATION OF INFUSORIA. 
the appearance of which, as De Quatrefages says, suggests that 
they are eggs.* We have made some examinations of our 
own on this subject, but it would be unnecessary to give the 
results in detail. We will simply state, that we have carefully 
examined the dust deposited in attics, also that floating in 
the air collected on plates of glass, covered with glycerine, 
and have found in such dust, in addition to the débris of 
animal and vegetable tissues, which last were by far in the 
greatest abundance, the spores of Cryptogams, some closely 
resembling those of Confervoid plants, and with them, but 
much less frequently, what appeared to be the eggs of some 
of the invertebrate animals, though we were unable to identify 
them with those of any particular species. We have also 
found grains of starch in both kinds of dust examined, to the 
presence of which Pouchet was the first to call attention. 
When compared with the whole quantity of dust examined, 
or even with the whole quantity of organic matter, both eggs 
and spores may be said to be of rare occurrence. We have 
not in any instance detected dried animalcules which were 
resuscitated by moisture, and when the dust has been mace- 
rated in water, none have appeared unti! several days after- 
wards, or until after a lapse of time, when they would ordinarily 
appear in any organic solution. 
Those who advocate the theory of spontaneous generation, 
on the other hand, will doubtless find, in the experiments 
here recorded, evidence in support of their views. While 
they admit that spores and minute eggs are disseminated 
through the air, they assert that no spores or eggs of any 
kind have been actually proved by experiment to resist the 
prolonged action of boiling water. As regards Vibrios, Bac- 
teriums, Spirillums, &c., it has not yet been shown that 
they have spores; their existence is simply inferred from 
analogy. It is certain that Vibrios are killed by being im- 
mersed in water, the temperature of which does not exceed 
200° Fahr. We have found all motion, except the Brownian, 
to cease even at 180° ahr. We have also proved by several 
experiments that the spores of common mould are killed, 
both by being exposed to steam and by passing through the 
heated tube used in the experiments described in this article. 
If, on the one hand, itis urged that all organisms, in so far as 
the early history of them is known, are derived from ova, and 
therefore that from analogy, we must ascribe a similar origin 
to these minute beings whose early history we do not know, 
* See an abstract of Pasteur’s “ Researches on Spontaneous Generation,” 
‘Am. Jour. Science and Art,’ vol. xxxii, J, 1861. 
