IN THE AIR THERE ARE LIVING GERMS 95 



bottom of the liquid if one leaves it in repose. We may 

 then decant the liquid above them, wash them, reunite 

 them finally in a little volume of water and study them. 

 And behold what we have! Look and tell me if there are 

 not there present corpuscles, spherical globules (Fig. 9), 

 round or oval bodies, so like the spores of cryptogams 

 or the eggs of Infusoria that no micrograph could dis- 

 tinguish them. As for their number, we find many 

 thousands in a little plug of cotton through which has 

 been passed for twenty-four hours a moderate current 

 of air, and as we count only the largest of these globules 

 figured here, those which have a clearly organized aspect, 

 while we leave aside the smallest, which are evidently 

 the most numerous, failing to distinguish them from 

 amorphous elements, you must conclude that there is 

 constantly present in the air in a floating state the means 

 of life for all the infusions which you put in contact 

 with it." 



IV 

 IN THE AIR THERE ARE LIVING GERMS 



"But," you will say, "what assurance have you that 

 these particles of dust which you have shown us are 

 living, or at least that they contain something living? 

 That is also easy to prove. We take the flasks of 

 Spallanzani, or of Schwann, for, mark it, I do not in- 

 troduce any new method of work, I am content with 

 operating well where others operated badly, with avoiding 

 causes of error which rendered the experiments of my 

 predecessors uncertain and contradictory. We take 

 then a flask containing a vegetable or animal infusion: 

 draw out the neck of it in a flame, then boil the liquid 

 in order to destroy by heat everything living that it 



