FINE STRUCTURE 39 



pseudopodia which he called ''radicules" (Fig. 7A). This would 

 account for the observation that coeruleus even at low magnification 

 shows a green, stellate foot. In side view after long attachment 

 Andrews observed that the stentor is chiefly anchored by the 



ackulsir psevudopod : j-a^a.nt 



Fig. 7. Holdfast of S. coeruleus. 



A. Underside of attaching holdfast, showing ectoplasmic 

 projections ("radicules") and active, undulating cilia said to 

 convert into thicker, acicular, attaching pseudopods. 

 B. Side view. (After Andrews, 1945.) 



acicular and lobose pseudopodial processes, Hke a balloon anchored 

 by ropes (Fig. 7B), the openings between which would preclude 

 any suction. If forcibly detached, the holdfast remains somewhat 

 intact for a while and is so sticky that if touched with a needle 

 adherence is firm and immediate. But later, or when the animal 

 detaches itself at will, the holdfast is withdrawn. Then, according 

 to Andrews, its structural parts resume their former forms and 

 functions, which would imply that the striping of the pseudopods 

 again takes the form of the posterior cell wall and the aciculars 

 transform back into cilia. However this may be, it follows that 

 structureless cytoplasm is not the sine qua non of attachment. 



