CHAPTER 7 



THE WORK OF WOLFF: 

 "ON THE SPECIAL ESSENTIAL TOWER" 



In order to conclude a summary of Wolff's activities in 

 embryology and to characterize them completely, it is neces- 

 sary to stop at the idea which he frequently considered 

 central to development and which was so differently evaluated 

 subsequently. The idea is that of the essential power. In 

 Wolff's works reviewed above, the essential power was mentioned 

 either generally or sometimes in a very hazy form, or it was 

 mentioned casually without sufficient explanation. Apparently, 

 at the end Wolff found it necessary. to explain his point of 

 view on this subject more definitely, and he felt the need to 

 examine scientifically the power's control over the activities 

 of organisms. 



In 1782 the Petersburg Academy of Science, under Wolff's 

 initiative (25), announced competition (26) for a prize on 

 the question about the nature of the feeding powers. The 

 subject of this work was formulated in the following manner. 1 

 In the introduction to the question, it was asserted that the 

 nutritional juices were distributed among even those parts 

 of the animal organism, such as the epidermis, nails, hairs, 

 and horns, which, it was claimed at the time, were devoid 

 of blood vessels. Further, it was noted that in the early 

 stages of development of the embryo, in which there was not 

 yet a heart, the blood vessels and the nutritional juices 

 were also distributed homogeneously. From this it was concluded 



1 . The questions for the competition were given in Latin and 

 submitted to the below-discussed manual "Zwo Abhandlugen 

 etc." Here a shortened statement of the introductory part 

 of the question is given. The text of the questions 

 themselves is given in literal translation. 



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