The argument most often urged against the idea that life exists in Mars is that there is no atmosphere in that planet, or if there is one it is so rarefied that it could not sustain life as we know it. According to Proctor, we have heretofore been led to consider the planet's physical condition as adapted to the wants of creatures which exist upon our own Earth rather than to ascertain the conditions which might obtain to enable life to exist on the surface of other planets. It is highly probable that if an air-breathing animal of our earth were instantly immersed in an atmosphere as rare as that of Mars, it would perish in a short time. Precisely what a species through thousands of generations of selection and survival might adapt itself to, is an open question. Leaving this contention for a moment, let us consider the almost infinite variety of conditions under which life exists on our globe, and we shall find that any and all conditions which the surface of Mars may offer, if experienced gradually through successive generations, would not be inimical to terrestrial life from the lowest to the highest, including even man. Mr. Garrett P. Serviss, in discussing the question of life, in his book "Other Worlds," said: "Would it not be unreasonable to assume that vital phenomena on other planets must be subject to exactly the same limitations that we find circumscribing them in our world? That kind of assumption has more than once led us far astray even in dealing with terrestrial conditions. It is not so long ago, for instance, since life in the depths of the sea was deemed to be demonstrably impossible. The bottom of the ocean, we were assured, was a region of eternal darkness and of frightful pressure, wherein no living creatures could exist. Yet the first dip of the deep-sea trawl brought up animals of marvellous delicacy of organization, which, although curiously and wonderfully adapted to live in a compressed liquid, collapsed when lifted into a lighter medium." One has only to make himself familiar with the wide range of conditions under which life in various forms exists on the Earth, to realize that the introduction of Martian conditions here would not be such an overwhelming calamity, and if these conditions could be introduced by minute increments covering thousands of centuries, it is not unreasonable to believe that myriads of forms would survive the change, and among those that survive would be precisely the kinds that thrive under the most diverse conditions here--namely, man and the higher hymenoptera, the ants.