564 FRAGMENTS OF SCIENCE. 
viously written and believed regarding spontaneous gener- 
ation, brought also into view a world of life formed of 
individuals so minute so close as it seemed to the ultimate 
particles of matter as to suggest an easy passage from 
atoms to organisms. Animal and vegetable infusions 
exposed to the air were found clouded and crowded with 
creatures far beyond the reach of unaided vision, but per- 
fectly visible to an eye strengthened by the microscope. 
With reference to their origin these organisms were called 
" Infusoria." Stagnant pools were found full of them, and 
the obvious difficulty of assigning a germinal origin to 
existences so minute furnished the precise condition 
necessary to give new play to the notion of heterogenesis 
or spontaneous generation. 
The scientific world was soon divided into two hostile 
camps, the leaders of which only can here be briefly 
alluded to. On the one side, we have Buffon and Need- 
ham, the former postulating his " organic molecules," and 
the latter assuming the existence of a special "vegetative 
force " which drew the molecules together so as to form 
living things. On the other side, we have the celebrated 
Abbe Lazzaro Spallanzani, who in 1777 published results 
counter to those announced by Need ham in 1748, and 
obtained by methods so precise as to completely overthrow 
the convictions based upon the labors of his predecessor. 
Charging his flasks with organic infusions, he sealed their 
necks with the blowpipe, subjected them in this condition 
to the heat of boiling water, and subsequently exposed 
them to temperatures favorable to the development of life. 
The infusions continued unchanged for months, and when 
the flasks were subsequently opened no trace of life was 
fonnd. 
Here I may forestall matters so far as to say that the success 
of Spallanzani's experiments depended wholly on the local- 
ity in which he worked. The air around him must have 
been free from the more obdurate infusorial germs, for 
otherwise the process he followed would, as was long after- 
ward proved by Wymau, have infallibly yielded life. But 
his refutation of the doctrine of spontaneous generation is 
not the less valid on this account. Nor is it in any way 
upset by the fact, that others in repeating his experiments 
obtained life where he obtained none. Rather is the refu- 
tation strengthened by such differences. Given two experi- 
