CHAPTER II 

 MORPHOLOGY OF THE CELL 



The history of the discovery of cells has been very briefly outlined. 

 It was pointed out that, although cells had been observed by a number 

 of zoologists, it was not until 1839 that Schwann, in collaboration with 

 Schleiden, announced the theory that all living things, whether plants or 

 animals, were made up of these units of structure, the cells. This propo- 

 sition was called by its author "The Cell Theory," but it has been so 

 abundantly verified that the term theory is no longer a fitting one. 



Fig. 15. — Felix Dujardin, lSOl-1860. (From Locy' s Biology and Its Makers.) 



Errors. — As was to be expected, the theory contained some errors, 

 at least in details. Its founders thought of the cell wall as the important 

 feature. They had seen the nucleus within the enclosure formed by the 

 walls, but regarded it as being in the wall. Moreover the nucleus was 

 conceived to be the beginning of a new cell. Although the protoplasm, the 

 living matter of which the cell is now known to be composed, had been seen 

 by several investigators, neither the latter nor Schleiden and Schwann 

 attributed any importance to it. Schleiden called it gum, a name per- 



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