Last and First Men

this influence some of them might be held rigidly in position in relation to one another. Such was the case of the organs of sight. In early stages of evolution, some of the units had specialized for carrying minute globules of water. Later, much larger droplets were carried, millions of units holding between them a still microscopic globule of life’s most precious fluid. Ultimately this function was turned to good account in vision. Aqueous lenses as large as the eye of an ox were supported by a scaffolding of units; while, at focal length from the lens, a rigid retina of units was held in position. Thus the Martian could produce eyes of every variety whenever he wanted them, and telescopes and microscopes too. This production and manipulation of visual organs was of course largely subconscious, like the focusing mechanism in man. But latterly the Martians had greatly increased their conscious control of physiological processes; and it was this achievement which facilitated their remarkable optical triumphs. One other physiological function we must note before considering the Martian psychology. The fully evolved, but as yet uncivilized, Martian had long ago ceased to depend for his chemicals on wind-borne volcanic dust. Instead, he rested at night on the ground, like a knee-high mist on terrestrial meadows, and projected specialized tubular groups of units into the soil, like rootlets. Part of the day also had to be occupied in this manner. Somewhat later this process was supplemented by devouring the declining plant-life of the planet. But the final civilized Martians had greatly improved their methods of exploiting the ground and the sunlight, both by mechanical means and by artificial specialization of their own organs. Even so, however, as their activities increased, these vegetable functions became an ever more serious problem for them. They practised agriculture; but only a very small area of the arid planet could be induced to bear. It was terrestrial water and terrestrial vegetation that finally determined them to make the great voyage.