The great danger for a plant in a dry air is desiccation, we may expect Martian leaves to have thick cuticles, just as the cactus has. Moreover, since moisture will come to the Martian plant, as Mr. Lowell shows, mainly from below, and not as rain from above, coming in seasonal floods from the melting of the snow-cap, the typical Martian plant will probably be tall, and have its bunches and clusters of spiky blue-green leaves upon uplifting reedy stalks.     Of course, there will be an infinite variety of species of plants upon Mars as upon the earth, but these will be the general characteristics of the vegetation. Now, this conception of the Martian vegetation as mainly of big, slender, stalky, lax-textured, flood-fed plants, with great shocks of fleshy, needle-shaped or formless leaves above, and no doubt with as various a display of flowers and fruits as our earthly flora, prepares the ground for the consideration of the Martian animals. Everyone nowadays knows how closely related is the structure of every animal to the food it consumes. Different food, different animals, has almost axiomatic value; and the very peculiar nature of the Martian flora is in itself sufficient to dispel the idea of our meeting beasts with any close analogy to terrestrial species. We shall find no flies nor sparrows, nor dogs nor cats on Mars.     Still, there is plenty of justification if an artist were to draw a sort of butterfly or moth fluttering about, or ant-like creatures scampering up and down the stems of a Martian forest jungle. Many of them, perhaps, will have sharp proboscides to pierce the tough cuticle of the plants.

But—and here is a curious difference—there are perhaps no fish or fishlike creatures on Mars at all. In the long Martian winter all the water seems to drift to the poles and freeze there as now, or freeze as ice along the watercourses; there are only-flood lakes and water-canals in spring and summer. And so forms of life that trusted to gills, or any method of under-water breathing, must have been exterminated upon Mars ages ago.     The Martian air is thinner and drier than ours, and we conclude, therefore, that there is still more need than on earth for well-protected, capacious lungs. It follows that the Martian fauna will run to large chests.     Here, then, is one indication for a picture of a Martian animal—it must be built with more lung space than the corresponding terrestrial form. And the same reason that will make the vegetation laxer and flimsier will make the forms of Martian animal kingdom laxer and flimsier, and either larger or else slenderer than earthly types.     Since the Martian vegetation has become adapted to seasoned flood conditions, there will be not only fliers and climbers, but waders—long-legged forms. Well, here we get something —fliers, climbers, and waders, with a sort of backbone. Now let us bring in another fact, the fact that the Martian year is just twice the length of ours, and alternates between hot summer sunshine—like the sunshine we experience on high mountains—and a long, frost-bitten winter. The day, too, has the length of a terrestrial day, and because of the thin air will have just the quick changes from heat to cold we find on this planet upon the higher mountains.