64 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 

 found. 



Here T 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 Wyman, 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 expert- 



