COSMIC AND ORGANIC EVOLUTION. 679 



matter of the globe is in the gaseous form. The gases themselves are 

 differentiated into what we call oxygen, nitrogen, carbonic acid, and 

 aqueous vapor, each of which exerts its special influence in the econ- 

 omy of vital existence, and without any one form of which, so far as 

 we can see, life would be impossible. Another portion of the matter 

 composing the earth exists in the liquid state, the chief form of which 

 is water, of which more than half the weight of all organized beings 

 consists. Evidently without water nothing answering to our concep- 

 tion of life could exist. Of the solid matter of the globe there exists 

 the greatest heterogeneity, and it may be classified in a variety of 

 different ways. Many, though probably by no means all, of the so- 

 called distinct substances known to us are of direct value in the for- 

 mation of organic tissues, and certain of them are clearly indispen- 

 sable, so far as we understand their office ; as, for example, lime, phos- 

 phorus, iron, etc., etc. Certain of these substances are crystalline, 

 others colloid in their structure, the latter of which possess peculiar 

 adaptations to the formation of organic tissue. Finally, between the 

 solid and the liquid state there exist all grades of transition, thus 

 adding variety to the organic adaptations. 



As the universal law of concentration or integration proceeds to 

 reduce all these varied forms to one, and to cement all in a single ho- 

 mogeneous solid, it is met by the powerful but somewhat irregular 

 and erratic force of the solar radiations, reenforcing the inherent cos- 

 mical influences already so far overcome in the evolution of the planet 

 as to have brought it to its given state. The result of this conflict of 

 forces is the condition in which we find our globe. Without the aid 

 of the sun's rays, organic evolution might have been impossible. 

 Without the aid of the cosmical force of concentration, in a certain 

 way counteracting without neutralizing them, it would have equally 

 been impossible. With such a predominance of the one as has proba- 

 bly prevailed in the past, or of the other as will probably prevail in 

 the future, the particular form of evolution required to develop what 

 we know as life seems also beyond the range of scientific probability. 

 A few degrees more either of heat or of cold are sufficient to utterly 

 destroy it. Of the latter, we have a near approach to a positive ex- 

 ample m the state of things existing in regions round the poles of the 

 earth's axis. Of the former, artificial proofs are easy, and certain 

 desert regions of the globe constitute partial illustrations, easily com- 

 pleted by the imagination. 



We thus learn what a precarious thing life is, within what narrow 

 limits it is circumscribed, upon what slender conditions its possibility 

 depends ; contemplating which, we may be appalled to reflect how 

 small a portion of the concentrated matter of space must be presumed 

 to fall under these conditions. For, even if every world in space 

 passes through this organic period, its duration must be ephemeral 

 compared with the vast cycle of its existence. 



