I4 VETERINARY PHYSIOLOGY 



the frog or newt. Processes are pushed out, and these are 

 again withdrawn, or the whole cell may gradually follow the 

 process, and thus change its position. The processes are called 

 pseudopodia (false feet), and the mode of movement, from its 

 resemblance to that seen in the amoeba, is called amoeboid. 



The part played by the network (cytomitoma) and the more 

 fluid part (cytoplasm) in these movements is not clearly under- 



E 



Fio. 2. Diagram of a Cell to show structure of Protoplasm aud Nucleus. In 

 the protoplasm A, attraction sphere enclosing two centrosomes ; V, 

 vacuole ; C, included granules ; D, plastids, present in some cells. In the 

 nucleus E, nucleolus ; F, chromatin network ; G, liuiu network ; H, 

 kar3'osome or net-knot (WILSON). 



stood. The pseudopodia are at first free of network; but 

 whether the fluid is pressed out by contraction of the meshes, 

 or whether it actively flows out, is not known. In some cells 

 among the protozoa movements take place along some definite 

 line, and the reticulum is arranged more or less parallel to the 

 line of movement. Such contractile processes, from their re- 

 semblance to muscles, have been termed myoids. In other 

 protozoa the pseudopodia manifest a to-and-fro rhythmic waving 

 movement, which may cause the cell to be moved along, or may 



