BIOGENESIS vs. ABIOGENESIS 



205 



Fig. 107. — Tyndall's apparatus. 



The apparatus consisted of a chamber with glass front and windows {w) and with test- 

 tubes fitted tightly in the bottom. Air could enter the chamber by the tubes a and b, but 

 the entrance of particles floating in the air, like dust and bacterial spores, was prevented by 

 bending these tubes. A pipette (c) that entered the chamber through a rubber diaphragm 

 could be moved to place material in the different test-tubes. This pipette was plugged 

 with cotton at (p) when not in use. 



In the experiments, the chamber was tightly sealed and left undisturbed for a few days 

 until the particles floating in the air had settled to the bottom of the chamber, as indicated 

 by the fact that an intense beam of light, when passed through the windows, failed to show 

 its track within the chamber. Various nutrient fluids, like hay infusion, beef broth, etc., 

 were then introduced into the test-tubes by means of the pipette. A brine or oil bath was 

 placed under the chamber and the test-tubes boiled for five minutes. Although the chamber 

 was thereafter placed in a warm room, there was not a single unexplained case in which such 

 an infusion showed any signs of life. That the observed sterility was not due to any lack 

 of nutritive power in the infusions was proved by opening the door of the chamber and 

 permitting free entrance of the external air with its suspended particles, and by introducing 

 contaminated material into individual test-tubes through the pipette. (From Tyndall, 

 "Floating Matter of the Air," copyright, 1888, by D. Appleton & Co., reprinted by per- 

 mission.) 



