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 



FIG. 107. A, Three ciliated epithelium-cells from the human epididymis. (After Schiefferdecker.) 

 B, Paramcecium aurelia, a ciliate infusorian ; C, Hexamitus inflatus, a flagellate infusorian 



E easing six flagella (After Stein.) D, Human spermatozoa; a, head, b, c, flagellum. 

 sr Stohr.) E, Peranema, a flagellate infusorian, with its flagellum contracting, a> feebly, 

 ore strongly. 



immediately after the movement of the preceding cilium has begun 

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

 from above downward, the movement of each upper cilium slightly 



