462 THE BIOCOSMOS HISTORICAL. 



vey. But the triumph of the microscope came 

 two centuries later in the revelation of the 

 cell as the organic unit of Life. It is true that 

 the cell had been recognized, described and 

 even pictured by the observers of the seven- 

 teenth century. In fact the ancients had sup- 

 posed some such structural unit in both plants 

 and animals ; the same statement had been re- 

 peatedly made as a conjecture. But the 

 ocular proof of the cell-theory as well as the 

 formulation of it are assigned to the year 1838 

 in the work of two German co-laborers, Schlei- 

 den and Schwan, the one a botanist, the other 

 an anatomist. The latter declares that "there 

 exists one principle for the formation of or- 

 ganisms and that principle is the cell," sup- 

 porting the proposition by direct observation. 

 Then came the discovery of protoplasm (by 

 Dujardin) as ike common ultimate material 

 in plants and animals. The leading statement 

 here is that of Schulze (1861) that a cell is a 

 globule of protoplasm surrounding a nucleus. 

 It should be noted that Darwin's pivotal book, 

 Origin of the Species, had appeared two years 

 before, yet it hardly participates in this great 

 movement of microscopic biology. 



But no sooner has the cell concentrated the 

 attention of biologists than the question opens 

 concerning its function, its physiological char- 

 acter. If it contains the unitary process of all 



