8 LECTUEES ON BIOLOGY 



According to Cuvier, each of these groups is entirely 

 independent of all others, forms a distinct type, and is in no wise 

 correlated with another type. Moreover, not only are these main 

 groups entirely distinct, but each individual species again repre- 

 sents a definite invariable unit. This constancy and immu- 

 tability of the species is the corner-stone of Cuvier's theory. 

 To this he clung with incredible tenacity up to the hour of his 

 death, defending it in the face of all facts and with the most 

 patent sophisms. When, for instance, palaeontology had proved 

 that in past periods animal forms had existed widely differing 

 from the present species, Cuvier established his Doctrine of 

 Catastrophism, in order to preserve his dogma of the immuta- 

 bility of the species. According to this theory each period of 

 the earth's history had been distinguished by a fauna and flora 

 peculiar to itself. Enormous revolutions of the surface of the 

 earth, floods, earthquakes, volcanic eruptions, and glacial floods 

 had then at one blow wiped out the entire plant and animal 

 world, and thus terminated one period. On the new virgin soil 

 a new fauna and flora had been created, by a divine act, thus 

 possessing no connection either with the organisms in the pre- 

 ceding or in the subsequent earth periods. 



During Cuvier's time the great naturalist, Jean Baptiste 

 Lamarck, and with him, Geoffrey St.-Hilaire, strongly opposed 

 this dogma of the fixity of the species, but could not avail 

 against the almost unlimited authority of Cuvier who had then 

 been raised to the peerage of France. On the contrary, the 

 theory of descent suffered complete defeat in the debate between 

 Cuvier and St.-Hilaire before the French Academy in 1830, and 

 consequently disappeared for years from the scientific agenda. 

 How deeply this controversy affected the leading spirits of those 

 restless times is shown by a dialogue between Goethe, then a 

 very old man, and his friend Soret. It was on August 2, 1830 ; 

 the news of the expulsion of Charles X. from the throne of 

 France had just reached Germany and all the world was talking 

 about it. On the morning of this day Soret had called on 

 Goethe who greeted him with these words: 'Ah! what do you 

 think of this great event ? The volcano is in full eruption, 

 everything is aflame, and it is no longer possible to deal with the 

 matter behind locked doors.' 



