mechanists' consideration of non-organic processes. In order 

 to imagine clearly Wolff's opinions, we must pursue a thought 

 from one of the concluding paragraphs: "The basis for formation 

 of the plant bud and animal embryo is contained only in 

 the available substance capable of development, which is 

 supplied by the essential power." And later: "For the appearance 

 of the organized body of nature nothing is needed except a 

 substance capable of development, which by some means is 

 produced by nature." 



In the last (third) chapter of the dissertation, Wolff's 

 remark that attracts attention is that the working out and 

 proofs of his assumed principles of development (the essential 

 power and ability of solidification) must be continued in the 

 future. Wolff pursued this in the investigations and theoreti- 

 cal explanations in both his THE FORMATION OF THE 

 INTESTINE (1766 - 1768) and "On the Special Essential Power" 

 (1789) . 



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