ORIGIN OF LOWEST ORGANISMS. 25 



a sufficiently safe one that many of the corpuscles 

 found by M. Pasteur were spores of fungi ; and in the 

 next place, supposing this to have been established, 

 whether such spores were living or dead. These 

 questions would have been answered satisfactorily if 

 M. Pasteur could state that he had actually watched 

 the development of such corpuscles, in some suitable 

 apparatus, into distinct organisms. But any such 

 development, he distinctly states, he never witnessed. 

 He says* : "What would have been the better and 

 more direct course would have been to follow the 

 development of these germs with the microscope. 

 Such was my intention ; but the apparatus which I 

 had devised for this purpose not having been delivered 

 to me at a convenient time, I was diverted from this 

 investigation by other work." The evidence which 

 he does adduce, in subsequent portions of his memoir, 

 in order to prove that some of these corpuscles were 

 really " fertile germs," is almost valueless, because all 

 the facts are open to another interpretation, which is 

 just as much, nay, even more, in accordance with Baron 

 Liebig's than with his own doctrine of fermentation. 



But another most important consideration presents 

 itself. M. Pasteur's researches as to the nature of 

 the dust contained in the atmosphere enable him to 

 say nothing concerning the presence of Bacteria, 

 although he himself admits that these are generally 



* Loc. cit. p. 34, note l . 



