“Organic existence must everywhere be to a great extent the same. The elements that enter into the composition of organisms, are subject to certain laws of chemical affinity, that demand their own conditions, and will not operate when these conditions are absent. The chief of these are furnished by the radiations of the sun in our solar system and no doubt by those of the stars in other systems. These radiations impressed upon organized materials become light and heat and where they are either in excess or deficiency organic development is not possible. These conditions obtain throughout the solar system, and no doubt in every system composed of the same sort of elements. But of the solar system we can speak with some confidence, for we have been able to visit a considerable part of it. “The inhabitants of the different planets differ from each other in the same way that the various animal races of earth differ from each other. You have on earth four sub-kingdoms of intelligent animals; vertebrates, articulates, mollusks and radiates. These have all been evolved from a common worm-like ancestry, and each form possesses the potentiality of receiving an equally high development, both physically and mentally. The development of any of them in all cases depends upon the way they are impressed by their surroundings and the proper surroundings can develop high intelligence in either of the forms. On earth the highest development has happened to the vertebrate branch, but with us the articulates have always been the dominant branch, while the vertebrates have never attained to a condition above that of your salamanders and small lizards. The ascendant race with us as with you has always contributed to keep the others in the background, by destroying the most advanced and aggressive of them and pursuing them till none but the smallest, weakest and most harmless of their tribe remain. Indeed until this is done, the position of the ascendant race is not secure. Your own race has had experience of this in the struggle with and subjugation of other races. In the early history of the earth, it was for a long time doubtful whether it was to be dominated by the human family or by a tribe of reptiles. At that ancient period, a tribe of reptiles had become developed that walked erect on their hind legs, and whose fore limbs supported wings and terminated in excellent hands, having four fingers. There were several related families of these animals, some of which were almost or quite the equal of man in intelligence. The final triumph of man over these advanced reptiles, was due to his superior compact social organization. While they relied on their superior personal prowess and often fought single handed, men always fought in bands, and hung together in all their enterprises. The reptiles being finally vanquished and the tribes most advanced and most to be feared having been exterminated, the rest had two modes of escape. They could use their wings and thus