THE ORIGIN OF LIFE 



27 



phere of the box. After permitting the closed box to 

 stand for a sufficient time, this dust was found to settle 

 and the ray of light being passed through the side widow, 

 finding nothing to reflect it, was no longer visible. When 

 the contained atmosphere attained to this optical test of 



FIG. 2. TyndalTs chamber for investigating the spontaneous generation 

 of life. The front is of glass, as are the side windows, t, to. The optical test for 

 the purity of the contained atmosphere is made by passing a powerful beam of 

 light from the lamp, I, through the side windows. When the atmosphere con- 

 tains no suspended particles, the tubes in the bottom are filled through the 

 pipette, pc. (Tyndall.) 



purity, the tubes fixed in the bottom were cautiously 

 filled with putrescible fluids through the tube in 

 the rubber diaphragm. When filled, these tubes, the 

 bottoms of which it will be remembered projected below 

 the bottom of the chamber, were heated by applying a 

 pan filled with hot brine, and their contents boiled briskly 



