THE STORY OF NINETEENTH-CENTURY SCIENCE 



perhaps in our century than ever before, but it can 

 hardly be' said that much progress has been made tow- 

 ards a definite answer. At first blush the demonstration 

 that all the worlds known to us are composed of the 

 same matter, subject to the same general laws, and 

 probably passing through kindred stages of evolution 

 and decay, would seem to carry with it the reasonable 

 presumption that to all primary planets, such as ours, a 

 similar life-bearing stage must come. But a moment's 

 reflection shows that scientific probabilities do not carry 

 one safely so far as this. Living matter, as we know it, 

 notwithstanding its capacity for variation, is condi- 

 tioned within very narrow limits as to physical sur- 

 roundings. Now it is easily to be conceived that these 

 peculiar conditions have never been duplicated on any 

 other of all the myriad worlds. If not, then those more 

 complex aggregations of atoms which we must suppose 

 to have been built up in some degree on all cooling 

 globes must be of a character so different from what we 

 term living matter that we should not recognize them as 

 such. Some of them may be infinitely more complex, 

 more diversified in their capacities, more widely re- 

 sponsive to the influences about them, than any living 

 thing on our earth, and yet not respond at all to the 

 conditions which we apply as tests of the existence of 

 life. 



This is but another way of saying that the peculiar 

 limitations of specialized aggregations of matter which 

 characterize what we term living matter may be mere 

 incidental details of the evolution of our particular star 

 group, our particular planet even having some such 

 relative magnitude in the cosmic order as, for example, 

 the exact detail of outline of some particular leaf of a 



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