310 The Realm of Nature CHAP. 



IV. PHANEROGAMS (flvwering plants). 

 GYMNOSPERMS Pines and Firs. 

 MONOCOTYLEDONS Lilies. 

 DICOTYLEDONS Buttercups. 



397. Classes of Animals. Animals are more numerous 

 and varied in their kinds than plants, and their classification, 

 according to resemblances and differences, is in consequence 

 more complex. Species, genera, families^ and orders are 

 distinguished much in the same way as with plants, and 

 animals also are named after both genus and species. The 

 great groups into which they are divided (and the classes of 

 the last group), with typical examples, are as follows : 



PROTOZOA Radiolarian, Foraminifera, Amoeba, etc. 

 PORIFERA Sponge. 



CCELENTERATA Jellyfish, Sea-anemone, Coral. 

 ECHINODERMATA Starfish, Crinoid, Sea-urchin. 

 VERMES Worms. 



ARTHROPODA Lobster, Barnacle, Millipede, Spider, Insects. 

 MOLLUSCA Oyster, Snail, Pteropod, Cuttlefish. 

 PRIMITIVE VERTEBRATES Tunicate, Lancelet. 

 VERTEBRATA Fishes Flounder, Salmon, Shark. 

 . Amphibians Frog, Newt. 



Reptiles Turtle, Serpent, Lizard. 



Birds Eagle, Ostrich, Sea-gull, Sparrow. 



Mammals Kangaroo, Lion, Ox, Whale, Ape, 

 Man. 



398. Functions of Living Creatures. The simplest 

 organism or the unit-mass of any living creature is merely 

 a jelly-like speck made visible by means of the microscope. 

 Part of the jelly-like substance may form a darker nucleus in 

 the interior, and in some cases a tougher film is seen to sur- 

 round and contain the whole. The organism is said to consist 

 of a single cell. The jelly-like substance called protoplasm 

 is a complex kind of matter, the precise nature of which is 

 unknown, but it consists mainly of carbon, oxygen, and 

 hydrogen, with minute quantities of nitrogen, sulphur, and 

 phosphorus. Living protoplasm is continually undergoing 

 two opposite sets of changes building up or renewal, 

 and breaking down or decay. The process of build- 

 ing up, which is distinctive of living creatures alone, 



