THE CELL DOCTRINE. 77 



lowed of similar movements and changes in form, in 

 colorless blood-corpuscles, pigment cells, arid else- 

 where, led Kblliker* to express the conjecture that 

 the contents of all cells are contractile. Virchowf 

 attributed' the ciliary movement to a contractile sub- 

 stance. Leydig:]: and Ecker considered the move- 

 ments of the yolk spherules as phenomena of life, 

 and Kiihne§ had studied physiologically and chemi- 

 cally, sarcode and muscular tissue, and pointed out 

 the similarity of the phenomena presented in the act 

 of dying, by both. But all considered sarcode as 

 something difterent from the animul cell, as a body 

 sui generis. 



According to HseckelH the protoplasm or sarcode 

 theory, that is, the theory that the albuminous con- 

 tents of animal and vegetable ceils as well as the 

 freely moving sarcode of Rhizopoda, Myxomycetse,. 

 etc., are identical, and that in both cases this albu- 

 minous material is the original active substratum of 

 all vital phenomena, was brought forward in its ele- 

 mentary form by F. Cohnl" in 1850, and by linger in 

 1855.** Hseckel says also that it may be considered 

 one of the greatest achievements in modern biology 

 and one of the richest in results. It was further dc- 



* Kolliker, Wurzb. Verb., Bd. viii. 

 f Virohow, Archiv, Band v., 1858. 

 J Leydig, Handbuoh der Histologie, 1856. 

 g Kuhne, Miill. Archiv, 1859, p. 817. 

 II Quart. J. Mic. So. July, 1869, p. 223. 



^ P. Cohn, Naohtrage zur Naturgeschiohte des protococous plu- 

 vialis, Nova Acta Ac. Leop. Carol., vol. xxii, pars. 2, 1850, p. 605. 

 ** linger, Anatomie und Physiologie d. Pflanzen, 1855. 



7* 



