THE ANIMAL KINGDOM. 11 



But this important fact passed unnoticed. Buffon and 

 Lamarck still continued to look upon them simply as little 

 masses of animated gelatine. 



A French naturalist, Dujardin, reared up a complete 

 theory on these data. Accord- 

 ing to him the substance of the 

 animalcule represents a sort of 

 spongy tissue, capable of hol- 

 lowing itself out into accidental 

 cavities, which admit food and 

 expel it by means of an outlet 

 which opens for this purpose 

 in the surface of the body. A 

 strange hypothesis, according * Various Illfus01 ' ia or Microzoa. 

 to which the Microzob'n hollows out for itself stomachs in 

 its own substance and of its own free-will ! 



It is difficult to believe that such a theory held sway in 

 France long after the publication of Ehrenberg's magnifi- 

 cent work on the Infusoria, in which the learned Prussian 



2. Successive forms assumed by the Proteus. 



naturalist demonstrated, for the first time, that these crea- 

 tures, notwithstanding their extreme minuteness, possess in 

 some cases a surprisingly complicated internal organization. 



