11 



determine this point, but the matter was then allowed to rest in 

 abeyance until about ten years ago, when Dr. Charlton Bastian 

 recommenced hostilities, declaring for their spontaneous origin. 

 The opposing forces were led on the one side by Bastian, and on 

 the other principally by Pasteur, Burdon Sanderson, and Tyndall. 

 I need not enter into the details of the campaign; but a descrip- 

 tion of some of their experiments is necessary for my purpose. 



First, it was shown that a temperature below that of boiling 

 water is sufficient to destroy all the visible living organisms. 

 Unfortunately a fallacy occurred at this point which was the cause 

 of much contention, and some loss of time, before it was discovered. 

 Bastian performed the following experiment : — He partly filled a 

 number of small loug-necked flasks with an organic infusion. He 

 then heated the necks and drew them out into capillary tubes. 

 This being done he boiled the contents, and during the ebullition 

 he closed the flasks by melting the minute necks in a blow-pipe 

 flame. Notwithstanding these precautions, in many instances, 

 after a short time, organisms appeared in the infusions. Bastian 

 then came forward with his flasks and said if spontaneous 

 generation is not true, how is this to be explained ? He even 

 went so far as to throw down the gauntlet to Pasteur, and offered 

 to go to Paris and perform these experiments there in Pasteur's 

 own laboratory. 



Dallinger, of Liverpool, after this pushed the inquiry further. 

 He said, although yoix kill all the living organisms which are 

 visible, yet the germs, which are invisible, may still remain, and 

 these are probably more resistant to high temperatures. He 

 showed that brisk ebullition for fifteen minutes was required to 

 completely destroy these germs, and that the temperature neces- 

 sary to kill varies with the nature of the medium to which the 

 heat is applied. Klein has shown that even these precautions will 

 occasionally fail, and that absolute certainty of success can only 

 be ensured by at least a second boiling after about 24 hours. 



If the development of organisms is to be prevented, it is 

 not only necessary that the germs in the liquid itself be destroyed 

 but the vessels, with their stoppers, &c., must also be purified. 

 This is best done by exposing them for some time to a high 

 temperature. Such prepared infusions are usually spoken of 

 as being sterilized. As I shall have to use this word frecpently, 



