Elementary text-book of zoology, general Elementary text-book of zoology, general part and special part: protozoa to insecta elementarytextbo00clau Year: 1892 32 OEGAXIZAXIOX A>'D DEVELOPMKXT OF AXIMAL8 IX GENEEAL. the body; tlie latter, on the contrary, serve for movement and sensation, functions which are exchisively the property of animals (as opposed to plants). For the sake of clearness we will divide the vegetative tissues into two groups,—into cells and cell-aggregatas (epithelium), and into tissues of connective substance. In the tissues of animal life we distinguish muscular and n
Elementary text-book of zoology, general Elementary text-book of zoology, general part and special part: protozoa to insecta elementarytextbo00clau Year: 1892 32 OEGAXIZAXIOX A>'D DEVELOPMKXT OF AXIMAL8 IX GENEEAL. the body; tlie latter, on the contrary, serve for movement and sensation, functions which are exchisively the property of animals (as opposed to plants). For the sake of clearness we will divide the vegetative tissues into two groups,—into cells and cell-aggregatas (epithelium), and into tissues of connective substance. In the tissues of animal life we distinguish muscular and nervous tissues. This classification of the tissues has no other aim than to facilitate a general review of the different forms of tissue, and to render possible a criticism of their relationships; it lays no claim to establish an absolutely sharp line between the various groups. 1. Cells and cell-aggregates. Cells may either be free and isolated from each other, floating in a fluid medium, or they may be placed near one another forming part of an aggregation of cells spread out superficially. To the former belong the cells of the blood, chyle, and lymph. The blood of invertebrates, which is generally colourless, and Fig. 19.—Blood-corpuscles (af^er Ecker). a, colourless blood corpuscles from the heart of the fresh water mussel (Anodonta). b, from the caterpillar of Sphinx, c, red corpuscles from Proteus, d, from the smooth adder, d', lymph corpuscles of the same, e, red corpuscles of the froe^. /, of the pigeon, f, lymph corpuscles of the same, g, red blood corpuscles of man. the blood of vertebrates, which is with few exceptions red, consists of a fluid albuminous plasma containing numerous blood-corpuscles in suspension. These corpuscles are in invertebrates irregular often spindle-shaped cells, endowed with the capacity of amoeboid move- ment. In the blood of vertebrates, in addition to such colourless amoeboid corpuscles there are found red corpuscles (discovered by
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