THE CELL DOCTRINE. 65 



above mentioned, and, by and by, ulterior changes 

 take place, for the production of the elementary 

 parts of the tissues."* 



Thus did physiologists adhere to the original free 

 cell formation of Schleiden and Schwann. Singu- 

 larly, Dr. Carpenter,t who expressly states, in his 

 Manual of Physiology, edition of 1865, that he has 

 been led to the view of Professor Beale by compari- 

 son of the results of the recent inquiries of several 

 British and Continental histologists with those of 

 his own studies, says, a few pages further on (p. 150), 

 " JSTew cells may originate in one of two principal 

 modes; either directly from a previously existing 

 cell, or by an entirely new process in the midst of an 

 organizable blastema." He then proceeds to give 

 the two methods in detail, without in any way deny- 

 ing the latter. 



viRCHOw, 1858. 



Less than two years later, August 20th, 1858, 

 Prof. Virchow published his " Cellular Pathology, 

 as based upon Physiological and Pathological His- 

 tology." According to him, the cell is the only 

 possible starting-point for all biological doctrines. 

 This cell can only originate from a previously exist- 

 ing cell, taking its primary origin from the ovum, 

 and the Harveian maxim omne vivum. ex ovo, becomes 

 in its special application, omnis cellula e celluld. This 



* Todd and Bowman, The Physiological Anatomy and Physi- 

 ology of Man. Am. Edit., Philadelphia, 1857, p. 63. 



f Carpenter, Manual of Physiology. London, 1865. Note on 

 p. 14. 



6* 



