spontaneous generation, and especially his view of. the hidden 

 forces of the earth, which he claimed had power to produce 

 such remains, now for the first time were seriously ques- 

 tioned, although it was not till nearly two centuries later that 

 these doctrines lost their dominant influence. 



Leonardo da Vinci, the renowned painter and philosopher, 

 who was born in 1452, strongly opposed the commonly accepted 

 opinions as to the origin of organized fossils. He claimed that 

 the fossil shells under discussion were what they seemed, and 

 had once lived at the bottom of the sea. " You tell me," he 

 says, " that Nature and the influence of the stars have formed 

 these shells in the mountains ; then show me a place in the 

 mountains where the stars at the present day make shelly forms 

 of different ages, and of different species in the same place." 

 Again, he says, " In what manner can such a cause account 

 for the petrifactions in the same place of various leaves, sea- 

 weeds, and marine crabs ?" 



In 151 7, excavations in the vicinity of Verona brought to 

 light many curious petrifactions, which led to much specu- 

 lation as to their nature and origin. Among the various 

 authors who wrote on this subject was Fracastoro, who declared 

 that the fossils once belonged to living animals, which had 

 lived and multiplied where found. He ridiculed the prevailing 

 ideas that the plastic force of the ancients could fashion stones 

 into organic forms. Some writers claimed that these shells 

 had been left by Noah's flood, but to this idea Fracastoro 

 offered a mass of evidence, which would now seem conclusive, 

 but which then only aroused bitter hostility. That inundation, 

 he said, was too transient ; it consisted mainly of fresh water ; 

 and if it had transported shells to great distances, must have 

 scattered them over the surface, not buried them in the 

 interior of mountains. 



Conrad G-esner (1516-1565), whose history of animals has 

 been considered the basis of modern zoology, published at 

 Zurich in 1565 a small but important work entitled u De omnia 

 rerum fossilium, genere." It contained a catalogue of the 



