36 THE ORIGIN OF LIFE 



in an incubator and at temperatures very much 

 higher. 1 



In each of the solutions a considerable amount 

 of deposit was produced by the heat, and when, 

 as " controls," some of these tubes were opened 

 within a day or two after the heating, and por- 

 tions of this deposit were examined with the micro- 

 scope, no organisms of any kind could be found 

 amongst it; though, after the tubes had been ex- 

 posed for some weeks or months to the influence 

 of diffuse daylight or to heat in the incubator, 

 organisms of different kinds were then very often 

 to be found in abundance on the deposited silica 

 or ferric silicate, and there only. They were never 

 found in the supernatant fluid, which invariably 

 remained clear. The organisms, moreover, were 

 always motionless ; so that, as I then said, "If 

 organisms are not there at first, after the process 

 of heating, and if, after an interval, they are there 

 in abundance and are invariably stationary, clearly 

 they must have developed in the sites where they 

 are found." 



Details of many of the experiments were given, 

 illustrated by photographs of some of the organ- 

 isms found in tubes which had been heated to 



1 See Knowledge and Scientific Neivs, Aug., 1905, p. 199. 



