270 THE FOOD OF ANIMALS 



in the waters of the land. In these animalcules the pseudopods 

 are exceedingly slender, and united together into a viscid net-work 

 by which the food is entangled. The same device is present in 

 the shelless Fungus- Animals (Mycetozoa), of which one common 

 kind (^thalium) is found in the form of good-sized branching 

 yellow flakes (" flowers of tan") creeping upon heaps of spent 

 tan. Each flake has been constituted by the fusion of a large 

 number of minute organisms resembling amoebae, and is there- 

 fore in reality of a compound nature. 



ANIMALS WHICH FEED LIKE GREEN PLANTS 



Some account has now been given of both food and way of 

 feeding in typical carnivorous, vegetarian, and omnivorous animals. 

 To complete and round off this part of the subject some notice is 

 necessary of certain animals, belonging to various groups, which 

 subsist partly or entirely after the manner of green plants. An 

 average ANIMAL feeds upon very complex food, part of which is 

 in the form of solid particles, for the reception of which an in- 

 ternal digestive cavity is provided. In all the forms so far 

 described the food is complex as regards its chemical nature, 

 though it may be entirely liquid, as in Tape -Worms, &c., and 

 examples have also just been given of animalcules devoid of any 

 digestive cavity. PLANTS, on the other hand, subsist entirely 

 upon gaseous and liquid food, though to this there are partial 

 exceptions. And though certain colourless plants, of which fungi 

 (e.g. mushrooms, toadstools, mildews, moulds) are familiar ex- 

 amples, so far approximate to animals that they live upon more 

 or less complex organic substances, yet typical green plants 

 differ markedly from average animals in that their food is 

 simple as regards chemical composition. The power such plants 

 possess of building up complex living substance (protoplasm) 

 from water, carbonic acid gas, and dissolved mineral substances, 

 depends upon the presence of the characteristic pigment called 

 leaf-green (chlorophyll). Examination of one of the thin leaves 

 from a moss-plant will show that it is made up of cells (vol. i, 

 p. 469) bounded by membranes (cell -walls) and containing 

 living substance (protoplasm). Imbedded in the protoplasm are 

 a number of rounded granules of bright-green colour. These 

 are chlorophyll-bodies > and each of them is in reality a specialized 

 bit of protoplasm through which leaf-green is diffused. Similar 



