1912] on Lord Lister. 553 



Other Tjikories of Fermentation. 



Those obsorviitionsund conclusions of Schwann, Cagniard-Latonr, 

 Pasteur and Davaine were not generally known, and, where known, 

 were not generally accepted— other theories being still in tlie field. 



Besides the chemical theory of fermentation and putrefaction, 

 Llic believers in heterogeneous and spontaneous generation were still 

 many. Pouchet,* in 1859, made a systematized attempt to prove 

 the possil)ility of spontaneous generation, and even after the anti- 

 septic theory had been fonnulated, spontaneous generation was still 

 advanced by Bastian f and other observers who tried to demonstrate 

 that vital force and living matter may arise de novo under the 

 action of ordinary physical forces. 



Tyndall, Huxley, and Ray Lankester against 

 Spontaneous Generation. 



Sucli writings had the effect of confusing the issue and diverting 

 men's minds from the truth, and it was in no small measure due to 

 the powerful help of Tyndall, Huxley, and Ray Lankester that the 

 error was conclusively refuted. 



Dr. E. Ray Lankester (" Nature," Jan. 30, 1870) stated that he 

 had performed numerous experiments with turnip solution, made 

 under the conditions given in Dr. Bastian's book. No life was deve- 

 loped, a result contrary to that obtained by Bastian. 



Prof. Huxley (" Nature," Oct. 13, 1871) stated that he had seen 

 Dr. Bastian's experiments and preparations and expressed his belief 

 that the organisms which Bastian got out of his tubes were exactly 

 those which he put into them. 



Tyndall, the illustrious predecessor of Sir James Dewar at the 

 Royal Institution, submitted the question to fresh investigations. He 

 had gone over the ground on which Bastian took his stand and was 

 able to expose many of the errors by which experimenters were 

 misled. One very beautiful and convincing experiment was introduced 

 by Tyndall. He observed the fact that in a box, the sides of which 

 were coated with glycerine, all the particles of dust floating in the 

 inside air fell and adhered to the glycerine in the course of a few days. 

 The air is then optically pure. A transmitted ray of light tells the 

 moment when this purity is oVjtained. Tyndall proved that to an eye, 

 rendered sensitive by remaining in darkness for a few minutes, the 

 course of the ray is visible only so long as there are floating particles 

 of dust capable of reflecting or diffusing light. On the other hand, 



* Pouchet, Heterogenie ou Traite de la Generation spontan^e base aur 

 des nouvelles experiences. Paris, 1859. 



t Bastian, The Beginnings of Life, 1872. The Evolution and Origin of 

 Life. 



