LIVING MATTE 7? . 61 



body, and swarm spores are seen to issue from 

 the nucleus. 



There is another part of the structure of this 

 curious creature which must be noted, as it is pro- 

 bably very important, though its exact function, as 

 observed in this and other similar forms of life, has 

 not been as yet exactly determined. A little white 

 speck is seen in the woodcut of about the same size 

 as the dark one. This is the contractile vesicle ; 

 and it is very curious to see how it, as it were, opens 

 and shuts. The opening or expanding motion is 

 very slow : a little clear space is seen, which gradu- 

 ally enlarges until, attaining its maximum, it begins 

 to fade away, and suddenly collapses or shuts up as 

 if with a spring. In a moment or two it begins to 

 open again, and so on, expanding and contracting. 

 This is probably a respiratory or circulatory motion 

 of a very rudimentary character, and perhaps is to 

 keep up the proper supply of oxygen required by 

 the animal. 



The only other thing about the Amo?ba that can 

 be called structure is the membrane which envelops 

 its whole body, and which is so thin and trans- 

 parent that the microscope fails to reveal it, and its 



