GEOLOGY. 713 



if we ought to find more respirable gas in the air of the 

 country than in that of towns. Experience began by 

 invaUdating this view; then it was found that the respir- 

 able gas is nevertheless a little more rare in the latter 

 than in the midst of the fields. M. Houzeau, one of our 

 most able chemists, in some experiments carried on upon 

 a large scale, found that oxygen is really a little more 

 abundant in the depths of forests, which distil it incessantly 

 from every pore of their leaves, than in our towns, where 

 a hundred thousand mouths absorb and consume it. 

 ■ This is what we know for certain relative to the chemi- 

 cal composition of the air; let us now speak of its micro- 

 scopy, so easy to study, and which has yet given rise to 

 so many puerile fables. 



The ancient theogonies, full of mystery and poesy, 

 peopled space with an infinity of invisible and charming- 

 divinities, who animated every part of creation. The gnomes 

 were scattered in the depths of the earth, the fire had its 

 salamanders, the naiads sported beneath the crystal waters, 

 and the sylphs, light and diaphanous as the plains of air, 

 everywhere lent life to the atmosj^here in the long and grace- 

 ful gyrations of their dances. 



Modern philosophers, without being more precise than 

 antiquity, have been less happy. Instead of sjdphs, they 

 have filled, nay, surcharged the air with an incalculable 

 quantity of germs, always ready to shed everywhere 

 fecundity and life. Fiction for fiction, we like that of our 

 predecessors better; it is much more attractive, and, more- 

 over, much less crude. 



By means of these germs disseminated in every part, 

 and entering by myriads wherever the vehicle in which 

 they live finds access, the learned of the eighteenth cen- 

 tury explained the appearance of those innumerable swarms 



