AMCEBOID ORGANISMS. 55 



Naked cells, with kernels, like those represented in 

 Fig. 10 B, which are continuously changing, stretching out 

 and drawing in formless, finger-like processes, and which 

 are on this account called amoeboid, are found frequently 

 and widely dispersed in fresh water and in the sea ; nay, are 

 even found creeping on land. They take their food in the 

 same way as was previously described in the case of the 

 Protamoeba (vol. i. p. 186). Their propagation by division 

 can sometimes be observed (Fig. 10 C, D.) I have described 

 the processes in an earlier chapter (voL i. p. 187). Many of 

 these formless Amoebae have lately been recogiiized as the 

 early stages of development of other Protista (especially 

 the Myxomycetse), or as the freed ceUs of lower animals and 

 plants. The colourless blood-cells of animals, for example, 

 those of human blood, cannot be distinguished from Amcebfe. 

 They, like the latter, can receive solid corpuscles into their 

 interior, as I was the first to show by feeding them with 

 finely divided colom-ing matters (Gen. Morph. i. 271). How- 

 ever, other Amoebae (like the one given in Fig. 10) seem to 

 be independent " good species," since they propagate them- 

 selves unchanged throughout many generations. Besides 

 the real, or n'aked, Amoebae (Gymnamoebae), we also find 

 widely difiused in fresh water case-hearing Amoebae (Lep- 

 amoebae), whose naked plasma body is 'partially protectetl 

 by a more or less solid shell (ArceUa), sometimes even by 

 a case (Difflugia) composed of small stones. Lastly, we 

 frequently find in the body of many lower animals parasitic 

 Amoebae (Gregarinae), which, adapting themselves to a para- 

 sitic life, have surrounded their plasma-body with a delicate 

 closed membrane. 



The simple naked Amoebae are, next to the Monera, the 



