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“Man’s liquid life” is therefore a good name to have given to the blood; for this constantly changing “special fluid” is assuredly as important to man as is cellulose The structural component of plant cell walls; used here to contrast the rigid structure of lower life forms with the fluid nature of higher ones. to the lower organisms.
The distinguished scientist, Ernst Haeckel A prominent 19th-century German biologist and philosopher who popularized Darwinism., who has probed deeply into the workings of nature, in several of his popular works has rightly drawn attention to the fact that blood is in reality the latest factor to originate in an organism. If we follow the development of the human embryo The early stage of a developing multi-cellular organism. we find that the rudiments of bone and muscle are evolved long before the first tendency towards blood formation becomes apparent. The groundwork for the formation of the blood, with all its attendant system of blood-vessels, appears very late in the development of the embryo, and from this natural science has rightly concluded that the formation of blood occurred late in the evolution of the universe; that other powers which were there had to be raised to the height of blood, so to speak, in order to bring about at that height what was to be accomplished inwardly in the human being. Not until the human embryo has repeated in itself all the earlier stages of human growth, thus attaining to the condition in which the world was before the formation of blood, is