602 Oviginal Articles. | Oct., 
(Germany); and Mantegazza (Italy); whilst amongst those who 
maintain that the atmosphere is the chief source from which such 
forms spring, are—Schultze and Schwann, and Schroeder (Germany) ; 
Pasteur and Quatrefages (France); and there are many other biologists 
of note who accept the latter view, but whose conclusions are based 
rather upon induction than experiment. 
Taking first the views of the believers in heterogenesis, we have 
those of Dr. Pouchet, of Rouen, whose investigations, it cannot be 
denied, have been very elaborate and persevering. He finds in the 
dust of the air, “the detritus of the mineral crust of the earth, animal 
and vegetable particles, and the minutely divided débris of the various 
articles employed in our wants ;” but he says (after narrating what 
kind of animal remains he has found, these being unimportant in our 
inquiry), “ twice only in more than a thousand observations, have 
I observed one of those large ova of infusoria having a diameter of 
0,0150 m.m., denominated by naturalists ‘cysts.’”* Amongst the 
numerous experiments tried by Dr. Pouchet, in order to satisfy him- 
self that the “ova” of infusoria do not exist in the atmosphere, is 
the following :|— 
‘““By means of an inhaling flask, I caused 100 litres of air to pass 
through a safety tube, whose bulb contained two cubic centimetres of 
distilled water. At the end of eight days I was unable to discover a 
single animalcule or ovum in this small quantity of water, in which the 
latter themselves could not escape observation, now that they have been 
completely described and measured, and are well known in several 
species.{ On the contrary, if I place ina cubic decimetre of distilled 
water five grammes of fermentable substance, sheltered by a bell glass 
having a capacity of one litre, at the end ‘of eight days, and at a 
temperature of 18° C, the whole surface of the water is occupied by 
incalculable myriads of animalcules.” 
It would be impossible to follow Dr. Pouchet through his experi- 
ments, all of which lead him to the conclusion that “ spontaneous 
generation’ is the sufficient and sole explanation of the appearance 
of Protozoa in infusions; suffice it to say that he has examined the 
air of towns and of mountain heights, the dust from ancient temples 
and subterranean sepulchres, and nowhere has it yielded him the 
slightest evidence of “panspermie ;” the universal diffusion of living 
germs, 
Of Messieurs Jolly and Musset it is only necessary to say, that 
they have recently been the coadjutors of Dr. Pouchet, and that they 
testify fully to the accuracy of his statements.$ 
Leaving for a time the ranks of the champions of “spontaneous 
* «Comptes Rendus, March 21, 1859: translated in the ‘ Microscopical 
Journal,’ 1860, p. 130. 
+ Loe. cit. p. 134. 
{ I presume Dr. Pouchet refers to “ cysts,” for Balbiani’s discoveries were not 
published until two years afterwards. 
§ They also tried some independent experiments, which will be found described 
in the ‘ Microscopical Journal,’ new series (1861), p. 47, to prove that “ spon- 
taneous generation”? may take place in the infusions inserted in the cavities of 
fruits. I must leave the consideration of these to scientific judges, but do not 
deem them sufficiently important for transcription here. 
