428 PLANTS AND THE ATMOSPHERE, 



possess, and because they would have been suffocated by the carbonic acid and 

 nitrogen . which were tbeo in the ascendency. Thus the primary strata of sedi- 

 mentary rocks contain no animal remains. As a compensation, however, the 

 earth was as favorably situated for the production of plants as it was unfavor- 

 ably for the support of animals; soon it became covered with luxuriant forests? 

 of which the accumulated remains have formed coal. In that mineral are found 

 all the species which then existed. They were gigantic Equisetaceae, tree-ferns 

 worthy of comparison with our oaks, and Cycadaceae surpassing in height the 

 most magnificent objects which the vegetable kingdom has now to exhibit. While 

 these immense deposits were being made, the oxygen, disengaged little by little 

 by the action of the sun, enriched the atmosphere and prepared for the birth of 

 the Animal 4iiingdom. Soon these early forms varying from age to age, made 

 their appearance. At the period when coal beds were forming, the forests were 

 populated by great reptiles, cold blooded animals requiring little oxygen ; but it 

 was not till after the almost entire disappearance of the carbonic acid that 

 mammals which had waited for a richer atmosphere came upon the scene. 



There are certain timorous ignoramuses who ask in all sincerity, what will be- 

 come of the earth and of themselves, when man has burned out all the coalfields? 

 What will become of us, good people ? I am about to tell you : coal will have 

 again become carbonic acid, oxygen will have disappeared, and monster Vegetatioa 

 will return : but if it is true, as certain people would have us believe, that animal 

 species developing little by little, rise from primitive forms up to man, the return 

 of the elements to their starting pbint should bring man back to his origin by aa 

 inverse degeneracy. The fact of having had crocodiles among our ancestors might 

 be allowed ; but to see in prospective a posterity composed of ichthyosauriana 

 is the most dreadful of all metempsychoses 1 



To return to graver matters. If we are ignorant of the mechanism of living 

 organs, we at least know the functions which they fulfil, and can clearly express 

 the part which they play in the physical world. With the water and nitrogenous 

 matter which they take from the soil, with a gas which they collect in the atmos- 

 phere, plants compose the organic matter which they accumulate in their tissues, 

 and hold in those fur the use of animals. The vegetable kingdom seems to be a 

 great laboratory, a producing workshop (Fr. atelier de production in opposition to 

 atelier de construction, factory), in which every plant has the same function of 

 constituting substances as varied in their composition as the plants themselves are 

 in form. To this common character we must add another, which is, that receiving 

 as primary materials, carbonic acid and water (substances which have been 

 burned) plants are able to expel the oxygen and extract the carbon and hydrogen 

 to which they restore the power of again being burned. These chemical actions 

 take place in their organs, which are, however, only the seat of them ; the cause 

 is external, it comes from the sun. Aijimals have a mission of a diametrically 

 opposite character. They do not create, but destroy : in place of solidifying gases 

 and liquids, they separate and return thera to the atmosphere; finally, far from 

 restoring bodies to a combustible state, they burn them. Herbivorous animals ex- 

 tract all their nourishment from plants-: -they transform a part of it into carloaic 

 acid and water, and stow away the remainder in their proper organs. The carni- 



