FRESH- WATER RHIZOPODS 139 



point in time of animal life, and that their agency in 

 the construction of many rocks of the globe has not 

 been equalled by that of higher or more visible 

 forms. We cannot go lower in the scale of animal 

 life. The rhizopod is the simplest of simple animals. 

 It has no internal cavity like the body-cavity of 

 higher animals ; it has no mouth, neither has it a 

 stomach, nor a trace of an intestine. It is devoid ot 

 a nervous system, and possesses no fixed organs ot 

 any kind. Its negative possessions, to use an 

 Irishism, are far in excess of its real ones, reminding 

 us of Sydney Smith's remark to a person boasting of 

 his own knowledge : ' All you don't know would fill 

 a very large book.' 



The rhizopod is a mere speck of jelly or sarcode 

 (Gr. saw, flesh ; cidos, form), yet it moves about with 

 the apparent purposes of more complex creatures. 

 Of these creatures the late Professor W. B. Carpenter 

 remarked : 



'Laying hold of its food without members, swallow- 

 ing it without a mouth, digesting it without a stomach, 

 appropriating its nutritious material without absorbent 

 vessels or a circulating system, moving from place 

 to place without muscles, feeling (if it has any power 

 to do so) without nerves. . . . And not only 

 this, but in many instances forming shelly coverings 

 of a symmetry and complexity not surpassed by 

 those of any testaceous animals,' i.e. animals that 

 have shells. 



Most members of this extensive group of tiny 



