t 679 ] 



terms used in the above scheme, will be of some use in get- 

 ting a fairly intelligent idea of the classification of the animal 

 kingdom given in the scheme. 



1,174 .Protazoa. The characteristic features of this class 

 of animals are, they are simply little masses of protoplasm, 

 without definite organs or a definite body cavity. They have 

 no nervous, digestive or circulatory systems. The proto- 

 plasm is not surrounded by a cell-wall as in the case of 

 vegetable cells and the protozoa are therefore able to throw 

 out pseudopods i. e., prolongations of the protoplasmic mass 

 of which their body is composed, when they notice any food 

 substance before them. Thus they possess volition which 

 characterises even the lowest member of the animal kingdom. 

 Looked at under the microscope these lowest animals present 

 at least three common characteristics: (i) they are nucleated 

 masses of protoplasm; (2) besides the nucleus they have a 

 contractile vesicle, a sort of rudimentary heart ; (3) the masses 

 of protoplasm are full of granules. The Gregarinidae and 

 Rhizopoda are reproduced by fission at the nucleus. For- 

 aminifera are encased in shells of calcium carbonate, a 

 particle of chalk being a mass of such shells. Radiolaria are 

 encased in shells of silica. They have a distinct mouth. In- 

 fusoria also have a distinct mouth, but no stomach. They 

 multiply not only by fission but also by conjugation and 

 gemmation : Infusoria grow abundantly in rotting animal 

 matter in presence of water. They are either ciliated or 

 flagellated. 



1,175. C eel enter ato* These have both mouth and a 

 body-cavity ; but no nervous system, no circulatory organ, no 

 blood. They have distinct stinging organs. Reproduction 

 takes place both sexually and by segmentation. They usually 

 live in colonies (e.g. sponges and corals). They are sometimes 

 polymorphic in character, i. e. possessing more than one 

 form and the same form repeats itself at regular succession 

 by a pro^jss which is knovva as alternation of generation. 



