!6o TffE ANIMAL KINGDOM. 



polygastrica, or many-stomachs ; but what were taken for 

 numerous stomachs have now, by the aid of our improved 

 microscopes, been shown to be merely the particles of 

 food above alluded to, embedded in the soft substance of 

 the body. The smallest known animalcula is the Monad, 

 which seems like the merest speck of gum moving freely 

 in the water (Fig. in). The im-. 

 mense number of Infusoria is 

 caused by their rapid increase ; 

 sometimes buds grow out of 

 their sides (as in the Hydra 

 already mentioned), at others, 

 numerous ova or eggs are given 

 Fig. in. out ; but the most frequent way, 



THE INCREASE OF A j s by division. Thus, in the 

 MONAD. \ . 



drawing (Fig. in) you will ob-. 



serve that the lowest Monad has become something 

 like the figure 8; the narrow part grows smaller and 

 smaller still, until at length the parts are separated, 

 and become two animals, as seen at a. One of the 

 Infusoria, called the Paramecium, has been observed to 

 divide itself every twenty-four hours, and each one of the 

 parts to divide again and again ; so that in a fortnight, 

 allowing for the same rate of increase, 16,384 animalcules 

 will have been produced, and in four weeks we should 

 have 268,435,456 from the same stock. 



The second division of the Protozoa is that called 

 Rhizopoda.* These animals possess no absolute form ; 

 hence the best known of them is called the " Amcebaf 

 diffluens" (Fig. 1 12). This animal consists of, as it were, 

 ' the merest speck of gum-water, which moves by throwing 

 out arms or feet from any part of its body, and again 

 contracting them ; but this little spe:k of jelly has its 



* Rhiza, a root ; pens, podos, a foot. t Amoiba t change. 



