THE SUN ANIMALCULE. 109 



greater transparency than the surrounding matter 

 which, after gradually swelling up to their ut- 

 most, give way so suddenly as apparently to shake 

 the whole fabric, causing a visible vibration in the 

 entire body of the animal. After a moment's rest 

 they are seen to be again expanding and again col- 



FIG. 20. Act'moaplucrlum eickornii. 

 In process of self-division or self-absorption. 



lapsing. This process is ever going on at regular 

 intervals, and these vesicles probably serve the 

 purposes of respiration and circulation. In the 

 inner zone are observed points or cells of greater 

 density than the rest, which are termed nuclei, and 

 are probably the prime seat of life and reproductive 

 power. For it is observed that, when a certain 

 process, now to be described, takes place, these 

 bodies, of which there are several, but never fewer 



