PROTOPLASM AND CELL 53 



identical hereditary qualities. This equal division of chromatin, 

 both qualitatively and quantitatively, has given rise to the thought 

 expressed in the phrase, ** continuity of protoplasm," and that 

 present chromatin comes from pre-existing chromatin. In 1855 

 Virchow, a German pathologist, declared the doctrine that all cells 

 must be derived from previously existing cells, in his statement, 

 '^omnis cellula e cellula." This supposes that in the first living 

 material created were inherent all of the possibilities which have 

 been realized in all living things that have existed since. 



References 



Cowdry, E. V. (editor) : General Cytology, Chicago, 1924, University of Chicago 



Press. 

 Heilbrunn, L. V.: Colloidal Chemistry of Protoplasm, Berlin, 1928, Borntraeger. 

 Sharp, L. W. : Introduction to Cytology, ed. 2, New York, 1926, McGraw-Hill 



Book Company. 

 Wilson, E. B.: The Cell in Development and Inheritance, ed. 3, New York, 1925. 



The Macmillan Company. 



