THE CELL DOCTRINE. 71 



substance. Ley dig* considered the movements of 

 the yolk globules as phenomena of life, and Kuhnef 

 had studied physiologically and chemically, sarcode 

 and muscular tissue, and compared the irritability 

 and changes after death, of both. But all consid- 

 ered sarcode as something different from the ani- 

 mal cell, as a body sui generis. Max Schultze, in 

 1861,t had first shown this analogy between sarcode 

 and the contents of the animal cell, and that the en- 

 tire infusorial world, simple or compound, is made 

 up of cells, thus extending the typical formative 

 element of Schwann to the entire organized creation. 

 So much for the relation of sarcode to the animal 

 cell. 



The comparison between sarcode and the proto- 

 plasm of plants was undertaken by Unger, E. 

 Briicke,|| E. Haeckel,! Max Schultze,** and W. 

 Kuhne,tf and by their efforts, according to Strick- 

 er,|J our knowledge of the independent life of the 

 cell was extended, in a very short space of time, fur- 

 ther than in the twenty years previous. 



Unger (1855), had been struck with the close 



* Leydig, Handbuch der Histologie. 1856. 



f Kuhne, Mull. Archiv., 1859, p. 817. 



J Schultze, Max, Mull. Archiv, 1861, p. 17. 



I linger, Anatomie und Physiology d. Pflanzen. 1855. 



|| Briicke, E., Elementarorganism, Wien Sitzungsb. 1861. 



If Heckle, E., Kadiolaren. 1862. 



** Schultze, Max, Protoplasm der Khizopoden und der Pflanz- 

 enzellen. 1863. 



ff Kuhne, W., Protoplasm und die Contractilitat. Lpzg.: 1864. 

 JJ Strieker, S., Handbuch der Lehre von den Geweben des 

 Menschen und der Thiere, Leipzig : 1868, p. 3. 

 \\ Unger, op. citat, p. 280. 



