26. The thin air, however, is no bar to vegetation, the climate of Mars being not that of a mountain peak but of a plateau, a very different matter.
From these two factors, sufficient water and enough warmth, we see that the conditions on Mars are quite suited to habitability by organisms of some sort. This is one of the results which observations at the Lowell Observatory during the past fifteen years have established.
We now go on to the question of its present habitation by organic life, which is the one of most popular interest. Organic life needs water for its existence. This water we see exists on Mars, but in very scant amount, so that if life of any sort exists there it must be chiefly dependent upon the semi-annual unlocking of the polar snows for its supply, inasmuch as there are no surface bodies of it over the rest of the planet. Now, the last few years, beginning with Schiaparelli in 1877, and much extended since at Flagstaff haveshown:
27. The surface of the planet to be very curiously meshed by a fine network of lines and spots.
28. The better the planet has been seen, the more this singular mesh discloses itself. It is very much as if a veil was drawn over the whole surface of Mars.
29. The lines of the network are each wonderfully straight, as if they had been laid down with the utmost regularity.
30. They run into one another at definite points, sometimes as many as fourteen converging to one of these junctions.
31. Each is of the same width throughout, so far as we may observe.
32. They differ, however, as between themselves, some being much larger and more prominent than others.
33. Their average width is apparently from ten to fifteen miles, certainly not more, and of the finer sort running down to a mile or two.
34. At the places where they meet are small, round, dark spots, which have been called oases by the writer.
35. These oases are also of differing size.
36. The network has been found to extend not only over all the reddish ochre parts of the disk, but across the blue green ones as well, no part of the planet being exempt from them.