PROTOZOA 



3S 



have proved that Paramecium is potentially immortal. 



Nervous Systejn and Reactions. — On account of its rapid loco- 

 motion, Paramecium has been used a great deal in studies of be- 



^^^' ^.■'••••••'-,.'ii,'^-t^ 



-.>..«> : b: . 





^''^> ; 



Fig. 13^. Chilodon. (After M. ^4- MacDougall.) 5. Colpoda cucullulus. 

 (After Biitschli.) C. Podophyra sp., a Suctorian. (After Calkins, Biology of the 

 Protozoa. Courtesy of Lea and Febiger.) 



havior. Jennings has shown that Paramecium responds positively 

 to contact, gravity and to running water, and that its behavior with 

 reference to stimuli of light, chemicals, electricity and heat depends 



