176 Education through Nature 



3. PHYSIOLOGY, a, Movement, reflex action, and spon- 

 taneity; b, nutrition; c, digestion, respiration, and circula- 

 tion, etc.; d } reproduction, conjugation, and division; e, 

 death. 



u/: 



FIG. 13. 



Viewed from the ventral side, showing the anal spot; arrows 

 inside the body indicate the direction of protoplasmic cur- 

 rents, those outside the direction of water currents caused by 

 the cilia. 



w., water; a. n., anal spot; c.v., contractile vacuoles; f. v., 

 food-vacuoles, m., mouth; ce., oesophagus; v , vestibule; mac., 

 macron ucleus ; mlc., micronudeus; cu., cuticle; cor., cortex; 

 vric., trichocysts; c , cilia; endo., endoplasm; w. v., water- 

 tacuoles. 



