^Appendix. 163 



matter for the production of living beings, etc." This motive it 

 is easy to see grew out of the tendency of the geological studies of 

 the day, which show that the earliest remains of animal forms 

 found in the earth's crust belong to the lower orders and gradu- 

 ally ascend in successive epochs to man. Hence it was an easy 

 I do not say legitimate inference, that the higher orders had 

 been gradually evolved out of the lower. And as the deepest 

 and oldest geological strata show no organic remains it is a fair 

 assumption that at some time in the great past there was no life 

 on the globe ; and lience another easy inference, that the first 

 living beings which appeared were produced by spontaneous gen- 

 eration. This is the gist of the evolution theory and as an induc- 

 ing motive in Pouchet's advocacy of spontaneous generation it is 

 worthy of remembrance ; for let me again remind you that such 

 a question cannot in the nature of things be argued on the ground 

 of probability, but must be determined solely by experimental 

 evidence. 



Pouchet further asserted that he had repeated Schultze's ex- 

 periments with every possible precaution, but with totally differ- 

 ent results. These assertions attracted much attention, and a few 

 scientists sided with him, though the majority and among them 

 the most of the leading physiologists opposed him. The question 

 assumed different phases, and in January, 1860, it was made one 

 of the prizes of the Academy. Pasteur, at this point, took up 

 the matter and made the researches to which allusion has already 

 been made. His first step was to ascertain whether in reality 

 there are floating in the atmosphere spores of the microscopic 

 fungi or germs of the infusoria, for by this time the question was 

 confined almost exclusively to one point, viz : the atmosphere as 

 the supposed source of the organic germs. For this purpose he 

 passed air through a wad of gun cotton packed in a glass tube. 

 Then dissolving the cotton in ether and alcohol he was enabled 

 to gather in the deposit whatever floating particles had been 

 caught upon the cotton during the forced passage of the air. 

 Then examining these deposits with the microscope he found, 

 besides the easily recognizable matters such as starch-granules, 



