Presidential address. 25 



proved conclusively that ordinary air is thick with germs 

 which can be filtered out, the air being rendered optically 

 pure. But it was the great Pasteur [Plate III.] who went 

 a step further, and showed that germs really do exist in 

 the air capable of giving rise to the development of living 

 forms in suitable menstrua. 



1. Pasteur examined microscopically the cotton wool 

 which had served as strainer, and clearly saw germs. 



2. Having found them, he proved them able to give rise 

 to definite living forms, 



3. He showed that no change was effected in the con- 

 stituents of the air by the wool, by dispensing with the 

 latter altogether, and substituting a finely drawn-out tube 

 bent downwards, attached to a bottle containing putresci- 

 ble fluid. The fluid being carefully boiled, and the tube 

 sufficiently heated to destroy any germs which might 

 enter as the fluid cools, he demonstrated that it could be 

 set aside for any time and no life will appear. 



On the other hand, however, Dr. H. Charlton Bastian 

 believed that he was not only able to form protoplasm by 

 the combination of several organic substances, but that, 

 under his watchful care, lowly forms of infusorial life had 

 been generated from inorganic materials. 



Huxley grasped the opportunity, and made Biogenesis 

 v. Abiogenesis the subject of his address before the meet- 

 ing of the British Association at Liverpool, in the year 

 1870, and I well remember listening to his eloquent voice 

 on that occasion, and the subsequent discussion on the 

 subject, which took place in section D. It proved the 

 final death blow to spontaneous generation, and I am not 

 aware that anyone has since attempted to resuscitate it. 



But probably no error ever paved the way to more 

 important or far reaching truths than did the error of 

 spontaneous generation, for it led to the discovery of the 



