1038 Summary and Conclusions 



K. It is inexact to teach, as is ordinarily done, that plants must 

 have appeared on earth before animals, in order to purify the air 

 of the large quantity of CO., which it contained. In fact, germina- 

 tion, even that of molds, does not take place in air that contains 

 enough C0 2 to be fatal to warm-blooded animals. 



It is just as inexact, as I remarked long ago, to explain the 

 earlier appearance of reptiles with reference to warm-blooded ani- 

 mals by the impurity of air containing too much CO.,; reptiles, in 

 fact, fear this gas even more than birds, and especially more than 

 mammals. 



