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and that of the hill far over the valley of the Saline; from these shadows you obstruct the rays of light, and from these glimmering rays you begin to realize that these simple people, who had advanced so far as to have learned the use and value of salt, probably from the herds of mighty animals that came to lap the water of the springs, or to lick the salt-impregnated earth, had also learned that the sun dried away the water and left the salt; and as they could not take the sun down into the valley to the water, they carried the water to the sun; and here on this southern slope, which then, as it does now, caught the first rays in early morning, its noonday beams, and evening kiss, were ranged scores—probably hundreds—of these primitive vessels, in which the sun, by its direct rays and heat-laden, southern breath, was doing the work of evaporation, yet not unaided by man. Around in every direction you find evidence of this, for every stone—and there are myriads—has been through the fire. They have been heated to redness and plunged into the brine.

Now, you may say I am indulging my imagination. Well, be it so. If I am, my imagination keeps within the bounds of possibility; while yours would endow these primitive people, whose only implements or tools seem to have belonged to the rude age of stone, with a skill in handling them far beyond what we in this enlightened age possess, with all our appliances. And you do this to give a color of truth to an entirely imaginary process, not sustained by a single fact.


TO many persons the phenomena of instinct and intelligence in animals seem irreconcilable with any theory of the evolution of organisms through the action of natural causes, but the popular opinion upon this subject has undergone a very considerable change within the last half-century, so that the difficulty now presents itself and finds expression in a much more manageable form than would have been the case a few years since.

With regard to instinct, we can easily see that if animals of a given species are born with a constitutional tendency, or instinct, to perform a certain action under certain circumstances, this tendency may be improved and perfected by natural selection, provided favorable variations appear, and be inherited. If instinct varies in the different individuals of a species, the struggle for existence wall result

  1. A lecture from a course on "Biological Theories," delivered at the Johns Hopkins University, January, 1877.