PROTOZOA AND SPONGES. 439 



tliat the eye cannot recognise the process of extension 

 — stretch and extend their lines and lihns of delicate 

 jelly, till at length they have stretched right across the 

 field of view. The extension is principally in two 

 opposite directions corresponding to the long axis of 

 the shell ; though the branched and variously con- 

 nected films often diverge considerably to either 

 side of these lines, giving to the whole a more or less 

 fan-shaped figure. 



These films are as irregular in their forms and sizes 

 as the expansion of the sarcode oi Amoeba, with which 

 they have the closest affinity. Their only peculiarity 

 is their tendency to run out into long ribbons or at- 

 tenuated threads, which however coalesce and unite 

 whenever they come into mutual contact, and thus we 

 see the threads branching and anastomosing Avitli the 

 utmost irregularity, usually with broad triangular films 

 at the points of divergence and union. 



There can be no doubt that the object of these 

 lengthened films, which are termed pseudopodia, is 

 the capture of prey or food of some kind ; perhaps 

 the more sluggish forms of minute animalcules, or 

 the simpler plants. These the films of sarcode probably 

 entangle, surround, and drag into the chambers 

 of the shell, digesting their softer parts in temporary 

 vacuoles, and then casting out the more solid remains, 

 just as the Amoeba does. 



Though this beautiful array was so very delibe- 

 rately put forth, it is, as you perceive, very rapidly 

 withdrawn on any disturbance to the animal, as when 

 we agitate the water, by slightly moving or turning the 

 cover of the live-box. Another fact, of which you may 

 convince yourself, by watching manifest though small 



