ANATOMY AND PHYSIOLOGY 



He outlined his views in an epochal paper published in 

 Miiller's Archives in 1838, under title of "Beitrage 

 zur Phytogenesis." This paper is in itself of value, yet 

 the most important outgrowth of Schleiden's observa- 

 tions of the nucleus did not spring from his own labors, 

 but from those of a friend to whom he mentioned his 

 discoveries the year previous to their publication. 

 This friend was Dr. Theodor Schwann, professor of 

 physiology in the University of Lou vain. 



At the moment when these observations were com- 

 municated to him Schwann was puzzling over certain 

 details of animal histology which he could not clearly 

 explain. His great teacher, Johannes Muller, had 

 called attention to the strange resemblance to vege- 

 table cells shown by certain cells of the chorda dorsalis 

 (the embryonic cord from which the spinal column is 

 developed), and Schwann himself had discovered a 

 corresponding similarity in the branchial cartilage of a 

 tadpole. Then, too, the researches of Friedrich Henle 

 had shown that the particles that make up the epi- 

 dermis of animals are very cell-like in appearance. 

 Indeed, the cell-like character of certain animal tissues 

 had come to be matter of common note among stu- 

 dents of minute anatomy. Schwann felt that this sim- 

 ilarity could not be mere coincidence, but he had gained 

 no clew to further insight until Schleiden called his 

 attention to the nucleus. Then at once he reasoned 

 that if there really is the correspondence between veg- 

 etable and animal tissues that he suspected, and if the 

 nucleus is so important in the vegetable cell as Schlei- 

 den believed, the nucleus should also be found in the 

 ultimate particles of animal tissues. 



rot. nr.g 



