474 THE PROTOZOA 



simply that their substance is of a viscid or semifluid nature, and 

 that their bodies are not limited by a membrane ; consequently, 

 when the two halves travel apart in the process of division, the 

 substance of the body is drawn out into a connecting thread until 

 its surface tension overcomes its cohesion. On the other hand, 

 they exhibit nothing of cell-structure or of any other characteristics 

 which indicate any affinity to the Protozoa. Their type of organiza- 

 tion seems to be the simplest possible in a living body a mere 

 grain of chromatin without cytoplasm, and without a membrane 

 or envelope of any kind. In the latter respect they appear to be 

 of a simpler type of organization than any bacterium, and perhaps 

 represent more nearly than any other known organism the simplest 

 possible form of living being. 



Bibliography. For references see p. 504. 



Ite domum, saturce, venit Hesperus, ite capellce. 



