THE CELL THEORY 241 



whether it is examined in the vegetating point of a plant, or 

 in the young budding- organs of an animal." 



Wolff was contending against the doctrine of pre-forma- 

 tion in the embryo (see further under the chapter on Embry- 

 ology), but on account of his acute analysis he should be 

 regarded, perhaps, as the chief forerunner of the founders of 

 the cell-theory. He contended for the same method of de- 

 velopment that was afterward emphasized by Schleiden and 

 Schwann. Through the opposition of the illustrious physi- 

 ologist Haller his work remained unappreciated, and was 

 finally forgotten, until it was revived again in 1812. 



We can not show that Wolff 's researches had any direct in- 

 fluence in leading Schleiden and Schwann to their announce- 

 ment of the cell-theory. Nevertheless, it stands, intellectually, 

 in the direct line of development of that idea, while the views 

 of Haller upon the construction of organized beings are a 

 side-issue. Haller declared that "the solid parts of animals 

 and vegetables have this fabric in common, that their ele- 

 ments are either fibers or unorganized concrete." This 

 formed the basis of the fiber-theory, which, on account of the 

 great authority of Haller in physiology, occupied in the 

 accumulating writings of anatomists a greater place than 

 the views of Wolff. 



Bichat, although he is recognized as the founder of his- 

 tology, made no original observations on the microscopic units 

 of the tissues. He described very minutely the membranes 

 in the bodies of animals, but did not employ the microscope 

 in his investigations. 



Oken. In the work of the dreamer Oken (1779-1851), 

 the great representative of the German school of " Natur- 

 philosophie" we find, about 1808, a very noteworthy state- 

 ment to the effect that "animals and plants are throughout 

 nothing else than manifoldly divided or repeated vesicles, as 

 I shall prove anatomically at the proper time." This is 

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