24 THEORIES OF SPONTANEOUS GENERATION 



' bold adventure of the intellect '. However, the later Natur- 

 philosophen, G. Hegel (1770-1831), F. Schelling (1775-1854) 

 and L. Oken (1779-1851) extensively developed the idea of 

 generatio aequivoca. Thus, for example, Hegel stated that 

 the earth and the sea had a clear need to be vivified 

 " but in its general form, vivification seems to be generatio 

 aequivoca "', and further, in his Enzyklopddie he wrote that 

 " the earth and, in particular, the sea generate all sorts 

 of lichens, infusoria, innumerable phosphorescent living 

 specks ".*^ 



According to Schelling,** there is a complete identity 

 between the earth and the animal and plant world. The earth 

 itself is transformed into plants and animals because that 

 w^hich is called dead matter is merely the ' dormant animal 

 and plant world '. 



Oken,*^ who w^as a follower of Schelling, developed the 

 idea that the earth, in the course of its metamorphosis, 

 degenerates into carbon and that this, being mixed with water 

 and air, is converted into ' hydrated oxidised carbon ' which, 

 as a formless primaeval slime, acts as the basis of all organisms 

 which have a form. Every living thing arises from this slime. 

 At first, like the primaeval planets, it turns into spherical 

 globules (the globules of primaeval slime) or infusoria under 

 the influence of light. These later metamorphose into plants 

 and animals which afterwards, on putrefaction, give rise again 

 to infusoria. Moreover, it is also possible that spontaneous 

 generation of ticks, worms and such creatures occurs by 

 simple direct coagulation of the primaeval slime. 



Thus, we find in the works of Oken, along with a banal 

 conception of the spontaneous generation of life, the elements 

 of a specifically scientific prediction. He had already put 

 forward the theory of the development of life by the gradual 

 evolution of matter, although in a very confused form. 



While these discussions on natural philosophy were taking 

 place in the first half of the nineteenth century, a whole series 

 of experiments was carried out with the aim of establishing 

 or refuting the possibility of the spontaneous generation of 

 microbes. 



An exceptional amount of care and experimental skill was 

 expended on elucidating the significance of air in the appear- 



