118 THE MICROSCOPIST. 



great numbers of these cells with the materials which 

 they have produced and deposited. 



Haller, who has been called the father of modern physi- 

 ology, seems first to have conceived, though vaguely 

 (A.D. 1766), the idea of the essential unity of vital struc- 

 ture. 



In 1838, Schleiden and Schwann wrote on the elemen- 

 tary cell, the former treating of the vegetable, and the 

 latter of the animal cell. From this time may be dated 

 the origin of the cell doctrine. Much importance was 

 assigned to the distinction between cell-wall, cell-con tents, 

 nuclei, and nucleoli. 



In 1835, Dujardin discovered in the lower animals a 

 contractile substance capable of movement, to which he 

 gave the name of sarcode. 



In 1861, Max Schultze showed that sarcode is analo- 

 gous to the body or contents of animal cells, and that on 

 this account the infusorial animalcules possessed of inde- 

 pendent life were simple or compound. 



Examinations of this structure were made by numerous 

 observers, and the identity of many of its properties in 

 animals and vegetables established. To this structure 

 the name of protoplasm, rather than sarcode, has been 

 assigned. As this term has been somewhat loosely used, 

 so as to refer to it either in the dead or living state, Dr. 

 Beale has proposed the term bioplasm for elementary struc- 

 ture while living, and has given a generalization from 

 observed facts which has attracted much attention. He 

 distinguishes in all organic forms three states of matter: 

 First. Germinal matter or bioplasm, or matter which is 

 living. Second. Matter which was living, or formed mate- 

 rial. Third. Matter about to become living, or pabulum. 



Schleiden and Schwann considered the cell as a growth 

 from a nucleus, and to consist of a cell-wall and cavity. 

 In vegetable cells there seemed to be an external wall of 

 cellulose, within which was another, the primordial utri- 



