24 GENERAL PRINCIPLES OF ZOOLOGY. 



species ; this practical procedure cannot be carried out 

 theoretically; for there are males and females within the 

 same species which, apart from their sexual organs, differ 

 more from one another than do the representatives of differ- 

 ent species. Thus John Ray attained to the genetic defini- 

 tion when he said : for plants there is no other more certain 

 characteristic for determining species than their origin from 

 the seeds of specifically or individually like plants ; that is 

 to say, generalized for all organisms: to one and the same 

 species belong individuals which spring from similar 

 ancestors. 



The "Cataclysm Theory."- -With Ray's definition an 

 entirely uncontrollable element was brought into the con- 

 ception of species, since no systematist knew anything, nor 

 indeed could he know anything, as to whether the represen- 

 tatives of the species placed before him sprang from similar 

 parents. It was therefore only natural that the conception 

 of species put on a religious garb, since by resting upon 

 religious ideas it found a firmer support. Linnaeus said : 

 "Tot sunt species quot ab initio creavit infinitum Ens"; 

 with this he built up a conception of species upon the tra- 

 dition of the Mosaic history of creation, a procedure quite 

 unjustified upon grounds of natural science, since it drew 

 one of its fundamental ideas from transcendental concep- 

 tions, not from the experience of natural science. Almost 

 immediately Linnaeus's definition showed itself untenable, 

 and at the same time Paleontology began to make acces- 

 sible a vast quantity of material, in the form of extinct 

 animals deposited as fossils. With an odd fancy, the 

 fossils, being inconvenient for study, were for a long time 

 regarded as outside the pale of scientific research. They 

 might be sports of nature, it was said, or remains of the 

 Flood, or of the influence of the stars upon the earth, or 

 products of an aura scminalis, a fertilizing breath, which, 

 if it fell upon organic bodies, led to the formation of ani- 

 mals and plants, but if it strayed upon inorganic materials 

 gave rise to fossils. The foundation of scientific Paleon- 

 tology by Cuvier put an end to such empty speculations. 



