embryology; hence he gave the students an idea about the 

 existing theories. He did not commit himself openly to any 

 of the opinions and presented them as not more than "intel- 

 lectual conditions and conjectures." "Not adhering to them 

 and not getting into the discussions resulting from these 

 teachings," Pekken wrote, ". . .1 only intend to present 

 briefly the most important opinions and studies about the 

 beginning and origin of animals, about which (Albrecht von) 

 Haller so elegantly wrote in the entire sense of natural 

 science" ($ 495, pp. 323 - 324). 



The new living existence originates, in the opinion 

 of some, in the maternal organism under the influence 

 of natural creative force (by epigenesis) , and, in 

 the opinion of others , exists in the parent organism 

 from the beginning. This latter opinion exists in 

 the basic studies about the pre-existence 

 (praeexistentia) , or predesignation (praedelineatio) , 

 or the assessment and development of the fetus 

 (evolutio) . (5 498, pp. 324 - 325) 



It is wonderful that Pekken mentioned epigenesis in the 

 first place. No less important is the fact that he considered 

 epigenesis that theory of development which is concerned with 

 the influence of natural conditions, at the same time quietly 

 confirming that the studies about preformation, or evolution, 

 cannot be managed without the influence of the other forces. 

 Next he stated the opinions of the animal investigators, "the 

 famous man from Delft, Leeuwenhoek," Swammerdam, and Malpighi. 

 Turning to the question about the motivating forces of 

 development and labelling as "ridiculous opinions" all the talk 

 about this subject of "complicated sophistications," Pekken 

 rejected such opinions as those about "the accidental 

 attraction of the nutritional particles, about the internal 

 patterns, and also about the concurrence of the spontaneous 

 beginning, about the soul -foundation, and other s."^ 



Stahl's animistic vitalism is especially antipathetic to 

 Pekken, who wrote the following: "The famous Stahl has 

 confirmed that in the human, the soul itself organizes the 

 body; hence it must be in the embryo endlessly more intelligent 



6. Here, not mentioned by name, Descartes, Buff on, and Stahl 

 are considered. 



125 



