concisely, and completely expressed the correct idea that 

 the preformation theory, assuming the preformation of the 

 organism in the early embryo, as a matter of fact denies the 

 real development formation of living creatures. Wolff made 

 it his task to produce a theory of development, based upon 

 principles and laws (5 5) , and which "can show sufficient 

 basis of the origin of the living creature" (S 6) . The true 

 theory of development must show the causes of development of 

 the organism, i.e. must represent its philosophical cognition, 

 that being the real science of organized bodies ($ 10) . 

 According to Wolff, the doctrine about development, as related 

 to anatomy, is purely a descriptive understanding of living 

 bodies and the philosophical cognition of substances related 

 to their historical cognition; therefore the theory of 

 development can be called "rational anatomy" (§ 11) . In 

 his German volume, Wolff detailed the contrast of historical 

 and philosophical cognitions. The explanation of composition 

 of a whole from parts and the description of these parts 

 represents the task of the historical cognition. If the 

 knowledge comes not only from direct experiment, but also 

 from causes and bases, then this gives grounds for 

 concluding that the substance must be this and not another, 

 and that it necessarily possesses determined characters. If 

 this is the case, then it will not be historical knowledge, but 

 philosophical cognition.^ The theory of development must 

 explain the phenomena of nutrition and growth, and also the 

 formation of the constituent parts of the organism (§ 24) . 

 It must take into consideration all essential and also less 

 essential conditions, and it must investigate why this or that 

 process of development proceeds in one way and not in another 

 way ($ 25) . 



Already from Wolff's program, it is clear that he took 

 upon himself a task of extraordinary importance: to give the 

 general theory of the formation and development of living 

 creatures and its contrast to the false theory of ontogenesis, 

 which was unconditionally doctrinaire about preformation. He 

 underlined the importance of a theory founded upon facts 

 rather than upon groundless discussions. "I cannot agree in 

 any case," he wrote, "that it can be performed by those.... 

 who hold speeches about this subject, as if there were no 

 science, truth and grace" (5 4, Introduction) . 



3. THEORIE VON DER GENERATION, p. 8. 

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