THE APPEARANCE OF LIFE ON WORLDS AND THE 

 HYPOTHESIS OF ARRHENIUS.^ 



By Alphonse Berget, 

 Professor at the Paris Institute of Oceanography. 



The problem of cosmogony is one of those that has most disturbed 

 the mind of man. No question, indeed, is more perplexing than that 

 of findmg out whence comes the earth, whence comes the sun about 

 which it gravitates with its sister planets, toward what goal is it 

 carried by that slow evolution that it undergoes. 



To this question Laplace was the first to give a scientific answer. 

 Starting from the results of the observation of the nebulee, different 

 forms of which we can observe in the sky at different stages of their 

 history, he formulated, by a true flash of genius, that wonderful 

 theory that bears his name. According to his conception, an incan- 

 descent nebula, radiating its heat gradually toward cold space, would 

 contract as it cooled; these successive contractions would by degrees 

 have agglomerated the constituent matter of the nebula into a 

 "nucleus," at first gaseous, then igneous fluid, the sun. In propor- 

 tion as the dimensions of this revolving nucleus — the total mass of 

 which remained the same — was diminishing, its momentum of 

 inertia was also diminishing, its velocity of rotation was increasing, 

 and consequently the centrifugal force was increasing at the same 

 time. A depression was formed on the still plastic nucleus near the 

 axis of rotation; the equator expanded and gradually a ring was 

 detached from it, which on breaking gave birth to a new planet, by 

 the condensmg of the matter of which it was formed. This planet 

 began to revolve around the nucleus and on itself, in the same 

 direction as that of the rotary motion of the central nucleus. Thus 

 must the earth have been born, thus must have been born the other 

 planets, fragments detached from the central sun, and necessarily 

 containing the same chemical elements. 



When Laplace advanced this hypothesis, certain astronomical facts 

 that are known to-day were yet unknown, notably the inverse 

 rotation of the satellites of distant planets. Nothing was known of 

 the existence of new forces that modern physics has just discovered 



I Translated by pennission from Biologica, Paris, 2d year, No. 13, January 15, 1912. 



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