Organisms Consisting of One Cell 



such as an air bubble, or advance by springs, which recall 

 those of a hunting spider." The rapid movement ahead, 

 running against obstacles, backing off, changing directions, 

 and turning around, remind one of the performances of an 

 ant under similar surroundings. Jennings' statement that 

 they are "usually found running about on the bottom, or 

 on the surface of objects in the water," 3 is no more a figure 

 of speech than would be a similar remark about a rabbit.* 



i icriu: .). STVI.ON vc in \ MYTii.rs (AITI:I< PCTTKH). 



With reference to their food habits, Alaupas's characteriza- 

 tion of them as "hunter ciliates," is truly descriptive. 



By contrast the movements of Stenostoma are slow and 

 simple indeed. In it locomotion is accomplished almost en- 

 irely by surface cilia, and the well-nigh complete absence 

 differentiation among these, as contrasted with the high 

 gree of differentiation and specialization of the cilia of 

 Uylonychui, may be taken as a reliable index to the dif- 

 rence in locomotor activities of the two creatures. 



(b) Comparison of a Hadlolaruni and a Jelly-fish 



Carrying the comparison of unicellular, "simple" or "un- 

 ic" animals, with multicellular, "complex/' "true," ani- 

 ials still farther, we will take up a Uadiolarian for brief 

 Hisideration. Non -technical readers are particularly urged 

 to look through the volume of 140 quarto plates which il- 

 lustrate IlaeckePs great Challenger Report on this group. 



* .Irmtiiifzs copies this diairram from I'iitter showing a 

 "creeping alon Hie surface," which shows well the "belly" and the 

 "hack" sides of the creature and the way in which it uses its cilia as legs. 



