As every intelligent person knows, the remains of tropical plants and animals are found as far as explorations have yet reached, and puzzle philosophers to account for their appearance there. Some have thought that through the long course of ages the earth has gradually, and perhaps may be still gradually, shifting its axis, so that what is now the north may have been under the line. The following from a recent lecture by Mr. Blandet before the Geographical Society of Paris, if true, might account for it in another way, - for if the Sun was so large every part of the earth would be warmed about alike. We cannot of course decide between these theories. The student must take his choice. "Our earth went, during its course in space, through six periods: 1st. The chaotic period - absence of all vegetable and animal life. 2nd. Carboniferous period - the era of the immense vegetable growth, which absorbed the carbonic acid from the air, and the products buried during successive convulsions of the earth, extended through various zones, as well under the equator as near the poles. 3rd. The cretaceous period. 4th. The oecene period. 5th. The miocene period - the primitive vegetation leaves the poles, which cool down to below the temperature necessary for life; at the same time nature, more choice in its products, gives birth to animals more and more perfect. 6th. The last or quaternary period, is that in which we now live.

"The continuous condensation of the sun is alone sufficient to explain how it has been able to furnish the prodigious quantity of heat which it has radiated into space. The calculations have been made: if it condense only enough to diminish its apparent diameter one second of an arc, it generates an amount of heat equivalent to that which it emits in 18,000 years.

"In the beginning of our earth's existence, it rolled through a space of fire, the sun's heated gases were extending beyond her orbit.

The sun had then, as seen from the earth, a diameter of 180°; this slowly became reduced to 47°, next to 22°. next to 8°, and finally to 2° apparent diameter.

"Then the quaternary period began; the poles commenced to cool, and only the tropics received heat enough to sustain the luxurious vegetation of the former periods.

"The miocene period, or the time when the tropical flora prevailed on the tops of the Pyrenees and Alps, and at the poles, when the sun was 3°, or 180 minutes, or 10,000 seconds larger, we go back 194,000,000 years before 244,000,000 years. Paris had, even later still, a tropical temperature, and the eocene period existed 250,000,000 years before that time, or about 500,000,000 years previous to the present day.

"But the carbonaceous era consists of 777,-000,000 years more, making together about 1,500,000,000 years.

"The earth separated from the contracting planetary nebula some 4,300,000,000 years before, making, as a total for the time of its independent existence, about 6,000,000,000 years.