THE ORGANIZATION OF THE PROTOZOA 



51 



The pseudopodia of the filose type adhere firmly to organisms 

 suitable for food with which they come in contact, and it can be 

 observed that the prey is both held fast and killed by them, in- 

 dicating that the pseudopodia secrete some toxic substance in 

 addition to that of an adhesive nature. In the reticulose type, 

 diatoms and organisms of various kinds are entangled in the 

 pseudopodial network (Fig. 21), and are generally digested there 

 also. 



In a few cases pseudopodia exhibit a peculiar form of movement 

 known as nutation. An example of this is seen in the remarkable 

 Heliozoon described by Schaudinn (43) under the name Camptonema 

 nulans (Fig. 47), which possesses slender axopodia in which the axial 



FIG. 23. Four stages in the ingestion of an Oscillarian filament (/.) by Amceba 

 verrucosa. In A the amoeba has crept along the filament ; in B one end of 

 the amoeba is bending up, and is about to fuse with the rest of the body, 

 producing a twist in the filament ; in G two have been produced ; in D a 

 considerable length of the filament has been drawn into the amoeba, and is 

 twisted up into a stout coil. A, B, and C, are drawn at intervals of quarter 

 of an hour, D several hours later. After Rhumbler (34). 



filament does not extend the whole length of the pseudopodium. 

 The pseudopodia perform a slow rotating movement, and "describe 

 the mantle of a cone, sometimes acute, sometimes obtuse, remaining 

 stretched out straight for their entire length, and bending only at their 

 base." Similar movements are performed by the pseudopodia of 

 Trichosph cerium (p. 229) and Wagnerella (p. 246). In Camptonema 

 the pseudopodia also have the power of bending suddenly when 

 brought in contact with prey, which they capture like the tentacles of 

 a polyp. The bending takes place beyond the point at which the 

 axial filament ceases. Movements of this kind are transitional to 

 those seen in flagella. 



(2) Flagella are vibratile thread-like extensions of the protoplasm, 

 capable of performing very complicated lashing movements in 



