248 



GENERAL PHYSIOLOGY 



the fourth, and so on. A cilium never contracts spontaneously 

 out of order, it never makes a movement before the preceding 

 cilium in the row has moved; it always begins its movement 



i Z 3 



Fig. lOV. — Ay Three ciliated epithelium-cells from the hunum epididj-mis. (After Schiefferdecker.) 

 B, Paramacnuii aurelia, a ciliate iufusoriau ; C, Hexamitu^ iiiHati'S, a flagellate infusorian 

 possessing six flagella (After Stein.) J), Human spermatozoa ; o, head, 6, c, flagellum. 

 (After StOhr.) E, Peyanemay a flagellate infusorian, with its flagellum contracting, a, feebly, 

 6, more strongly. 



immediately after the movement of the preceding cilium has begun 

 and before it is ended. It thus happens that, considering the row 

 from above downward, the movement of each upper cilium slightly 



