THE STORY OF NINETEENTH-CENTURY SCIENCK 



where motion is, stasis is not. Sooner or later, in its 

 ceaseless flight through space, the dark star must col- 

 lide with some other stellar body, as Dr. Croll imagines 

 of the dark bodies which his " pre-nebular theory " pos- 

 tulates. Such collision may be long delayed ; the dark 

 star may be drawn in cometlike circuit about thousands 

 of other stellar masses, and be hurtled on thousands of 

 diverse parabolic or elliptical orbits, before it chances to 

 collide but that matters not : " billions are the units 

 in the arithmetic of eternity," and sooner or later, we 

 can hardly doubt, a collision must occur. Then without 

 question the mutual impact must shatter both colliding 

 bodies into vapor, or vapor combined with meteoric 

 fragments ; in short, into a veritable nebula, the matrix 

 of future worlds. Thus the dark star, which is the last 

 term of one series of cosmic changes, becomes the first 

 term of another series at once a post-nebular and a pre- 

 nebular condition ; and the nebular hypothesis, thus am- 

 plified, ceases to be a mere linear scale, and is rounded 

 out to connote an unending series of cosmic cycles, more 

 nearly satisfying the imagination. 



In this extended view, nebulae and luminous stars are 

 but the infantile and adolescent stages of the life his- 

 tory of the cosmic individual; the dark star, its adult 

 stage, or time of true virility. Or we may think of the 

 shrunken dark star as the germ-cell, the pollen-grain, of 

 the cosmic organism. Eeduced in size, as becomes a 

 germ-cell, to a mere fraction of the nebular body from 

 which it sprang, it yet retains within its seemingly non- 

 vital body all the potentialities of the original organism, 

 and requires only to blend with a fellow-cell to bring a 

 new generation into being. Thus may the cosmic race, 

 whose aggregate census makes up the stellar universe, 



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