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THE POPULAR SCIENCE MONTHLY. 



divided, and each, of the newly formed organisms receives its 

 share. These little beings are particularly entitled to our atten- 

 tion, because each higher organism is also originally evolved 

 from a naked egg-cell, and devoid of any membrane or cuticle.* 

 Moreover, such a cell shows essentially the same simple structure, 

 and moves about in the same manner as the amoeba — that is, by 

 the aid of pseudopodia. 



Hence the amoebae are one of the lowest forms of organisms 

 known ; they have remained on the lowest plane of development, 

 and, if one accepts, with Lamarck and Darwin, the evolution of 

 the animal world from a simplest beginning, these creatures must 

 be regarded as the original progenitors of all forms of animal 

 life. Of course, every one is at liberty to doubt such progressive 



evolution of organized beings ; but this 

 much is certain, the individual develop- 

 ment of each proceeds from a primary 

 state, which is not greatly different from 

 the structure of these amoebae. 



Fig. 2 represents a shell-bearing amoeba 

 (Euglypha), which is also to be found in 

 great numbers in the mud of wells. In 

 this organism the naked sarcode, which 

 consists of a substance similar to albumen, is covered and pro- 

 tected by a membranous envelope, or "carapace," from which, 

 through an opening, the pseudopodia (ps) appear. The little or- 

 ganism pictured in Fig. 3 stands in close relationship to the pre- 

 ceding (Centropyxis aculeata.) Its shell, made up of diatoms and 

 fragments of small particles of stone, shows thorn-like protuber- 

 ances. 



Fig. 3. 



Fig. 4. 



Fig. 4 makes us acquainted with the appearance of the flagel- 

 late infusoria. These are animals that have a delicate body, which 

 can be contracted, and at one end of which there is a filament (gf) 

 which is constantly in motion, and with which certain movements 

 are executed. This filament is in reality nothing else than a long 



* Authorities differ on the question as to whether the amoebae are covered with a mem- 

 brane or not. — Translator. 



