94 The Science of Life. 



the theory in all its details, but the story may be recom- 

 mended to the psychological historian as a labyrinth of 



error, with glimpses of truth at every turn. 

 BeifeTL Even Aristotle (384-322 B.C.), the founder 



Spontaneous o f Biology, believed in spontaneous genera- 

 Generation. . I*., 



tion, but he did not accept the current creed 



lightly. In point of fact he devoted no small space, and 

 no little ingenuity, to its discussion. Thus it was almost 

 exclusively in regard to invertebrate animals that Aris- 

 totle postulated spontaneous generation; except in the 

 case of a few fishes, such as eels (whose generation 

 was till very lately a complete puzzle), he held that ver- 

 tebrates arose as the result of pairing. As to insects 

 and the like, Aristotle was well aware that they were 

 male and female and reproduced sexually; he was even 

 aware of the partial parthenogenesis of bees' eggs, those 

 which become drones having a mother but no father: 

 what he asserted was, that spontaneous generation 

 occurred as well. He seems to have been especially and 

 naturally puzzled by the sudden appearance of internal 

 parasites, and by the occurrence of small animals in 

 putrefying substances facts which were not explained 

 until quite modern times. 



From Aristotle to Augustine, from Lucretius to 

 Luther, on through the long centuries the belief in 

 Mediaeval spontaneous generation remained unshaken. 

 Beliefs. Even a man like Cesalpino, who did some 



excellent botanical work, and had, long before Harvey, 

 some clear ideas as to the circulation of the blood, 

 believed that frogs might be generated from the mud 

 with the help of sunshine, and even suggested a similar 

 origin of the aboriginal Americans. The botanists were 

 no better than the zoologists. One of their favourite 

 notions was that the green dust which grows in damp 

 weather on trees and stones, which is now known to 

 consist of unicellular Algae, such as Pleurococcus, was a 

 standing evidence of the genetic connection between 

 the dead and the living, between the mineral and the 

 vegetable; even Bacon of Verulam believed in the 

 spontaneous origin of some higher plants, like thistles, 

 from dead earth; and the Italian botanist Matthioli 



