SEVENTEENTH AND EIGHTEENTH CENTURIES Z^J 

 from the simple elements through the mineral kingdom, vegetable kingdom, 

 and animal kingdom in a long line right up to man. The transitions in the 

 series are, from the modern point of view, ingenuously chosen: the flying 

 fish provides the transition between fishes and birds; the ostrich, the bat, 

 and the flying squirrel between birds and quadrupeds; the polypus and the 

 sensitive plant between animals and vegetables. But then he also declares 

 that the whole of this division is only approximate and that perhaps the 

 series is not as uniform as he has made it; that perhaps molluscs and insects, 

 lizards and frogs do not follow one another consecutively, but are in reality 

 collateral with one another. Just as the long evolutionary series of Bonnet 

 clearly foreshadows Lamarck's evolutionary theory, so the assumption of 

 parallel evolutionary groups represents a first hint of the type theory that 

 Cuvier founded and whereby he reformed the entire zoological system of 

 classification and rendered possible the approach of the modern descent- 

 theory. And as has already been pointed out, the points of agreement are 

 certainly not accidental; Bonnet enjoyed a great reputation amongst his con- 

 temporaries and the immediately succeeding age and was diligently studied. 

 Cuvier in particular has expressed his warm admiration for him and recom- 

 mended his writings for careful study; and other contemporary biologists 

 certainly knew his works and were to some extent influenced by them. 



In the foregoing have been mentioned those theories of Bonnet that 

 have proved to be the most vital for the development of biology, and con- 

 siderations of space forbid a detailed account of all the shrewd utterances 

 which this imaginative man of genius scattered throughout his writings; 

 for example, his striking criticism of vitalism. In spite of his religious fa- 

 naticism he gives a purely mechanical explanation of the bodily functions 

 and cites the pointed objection to the vitalists — mostly Stahl and his 

 school — that "souls" are particularly convenient to have when it is a 

 question of explaining the phenomena of life; they do everything that is 

 asked of them and their non-existence can never be proved. Another time 

 he gives a detailed analysis of the different organs in the same body that 

 are dependent upon one another and shows how a change in one organ must 

 inevitably react upon the others; and on still another occasion he describes 

 his observations regarding different mental impressions — a problem which, 

 as is well known, Goethe made the subject of exhaustive study. Thus Bon- 

 net was a man full of ideas; and though in a great deal he must appear out 

 of accord with our age, yet undoubtedly many of his ideas are nowadays 

 incorporated in the general consciousness. 



The experimental biological investigations that Bonnet made the basis 

 of his speculations were continued and considerably widened by Lazzaro 

 Spallanzani (172.9-99). Born at Reggio, the son of a lawyer, he studied law 

 at Bologna and at the same time took orders. He afterwards devoted himself 



