512 A NEW THEORY OF THE ORIGIN OF SPECIES. 



of a mixed fauna comprising representations of all the grand divisions 

 of the animal kingdom. This is shown in the Upper Silurian or 

 Devonian horizon in which the vertebrates make their appearance in 

 the form of fish. In the most ancient fauna, and that which has 

 become known most recently (that of the Lower Silurian or Cambrian), 

 all the grand divisions are still found, except that of vertebrates, each 

 represented by quite high t3"pes. It is a question to be decided 

 whether, lower down, in the sedimentar}' rocks hitherto considered 

 as azoic, there is really a living population, more widely scattered, 

 and reduced to the most rudimentary animals and plants — that is to 

 say, to protophytes and protozoans, as appears from the researches of 

 MM. Barrois, Bertrand, and Caveux. Yet it is none the less certain 

 that the ver}- important remark of Agassiz is true, and that, in the 

 Cambrian horizon, all the principal tj'pes appear simultaneously. We 

 perceive here a sort of explosion of universal life. 



In consequence of this the transformists are obliged to admit that 

 in the short space of time that corresponds to the deposit of the most 

 ancient fossiliferous rocks the first living beings must have undergone 

 all the evolutions necessary for passing from the state of a simple mass 

 of protoplasm to that of types characteristic of all the grand divisions, 

 the vertebrates only excepted. We are authorized to conclude that 

 the time during which the most ancient fossiliferous rocks were 

 deposited was short, because we can judge of it from their thickness, 

 which is nmch inferior to that of the subsequent strata. Therefore, 

 but a comparatively short space of time was required for the modifica- 

 tions by virtue of which the first living forms produced the principal 

 grand divisions. The Lower Silurian epoch was one of rapid trans- 

 formations, of active morphogenesis, of intensive mutations. If we 

 w ished to suppose that these wei'e caused by the Darwinian mechanism 

 of slow accumulation of minute variations, we would be obliged to 

 throw back the origin of life into an epoch inconceivabl}- beyond the 

 most ancient geologic epoch now known. 



In the same way, as other paleontologists have observed, among 

 wdiom is Dr. Chark'S A. White, the extraordinary flora of the Carbon- 

 iferous epoch developed abruptly. We know- nothing or but ver}' 

 little of the floras that preceded it. Its appearance and its extinction 

 were sudden. 



We might multiply these remarks relative to the abrupt explosions 

 of creation in living things. Here is another. The dinosaurian 

 lizards that abounded throughout the secondary" epoch, forming. 

 indeed, the dominant animal tj^pe, show an extreme variety taken 

 from any point of view. There were some gigantic ones, like Bron- 

 tosaurus, having a mass that wps certainly equal to that of four or 

 five elephants, others of small stature not larger than a domestic fowl. 

 The group included carnivora and herbivora, aquatic species and 



