INTRODUCTORY 13 



ing organic material, and forming a group intermediate between 

 the slime-moulds and the bacteria proper, and sometimes 

 classed among the latter. They are motile, rod-like organisms, 

 and multiply by simple division or fission. 



7. Schizophyta ("fission-plants" or "splitting plants"). 

 This group is, perhaps, the most important from our present 

 point of view, as it includes the Schizomycetes (fission-fungi 

 or splitting fungi), Bacteriaceae or Bacteria, and also their 

 close relatives the Schizophyceae or splitting algae, and the 

 Gyanophyceae, or blue-green fission-algae. The latter occupy 

 a somewhat higher position than bacteria in the scale, as they 

 possess the colouring matter, chlorophyll, along with other 

 pigmentary substances, and are therefore able to assimilate 

 carbon and build up its compounds under the action of sunlight, 

 whilst the bacteria do not possess chlorophyll, and depend upon 

 the breaking up of already formed organic matter, i.e. complex 

 animal or vegetable substances containing the carbon and other 

 elements necessary for their life. The nature of the cell-wall 

 also differs in these two groups or orders, being composed of 

 the carbohydrate or starch-like substance, cellulose, the most 

 abundant solid constituent of vegetable tissues, in the case of 

 the blue-green algae 1 ; whilst in bacteria, it is rather to be re- 

 garded as a condensation of the protoplasm or body-substance 

 itself. At the lower end of the fission-algae group, however, 

 and at the top of the fission-fungi or bacteria, there are 

 members of each group which have many characteristics in 

 common, which practically unite them into one continuous 

 series. 



CHIEF DIVISIONS OF THE ANIMAL KINGDOM 



A. Vertebrata or back-boned animals : mammals, birds, reptiles, 



amphibia, fishes, &c. 



B. Invertebrata (with no back-bone) : 

 I. Molluscs or shell-fish. 



II. Arthropods : crustaceans, insects, spiders, &c. 

 III. Echinoderms : star-fish, sea-urchins, &c. 

 IY. Vermes : worms, segmented and non-segmented. 

 V. Coelenterates : corals, sea-anemones, jelly-fish, &c. 

 VI. Porifera or sponges. 

 VII. Protozoa, or primitive animals. 



Classification of the Protozoa 



1. Ehizopoda, Gymnomyxa, or Sarcodina: mostly naked 

 amoeboid forms, locomotion being effected by the projection of 



1 This substance, cellulose, is the chief constituent of such vegetable 

 products as linen, cotton wool, paper, etc. 



