n THE PROGRESS OF SCIENCE 79 



Nature are specialised portions of a relatively 

 homogeneous materia prima which were origin- 

 ated under conditions that have long ceased to 

 exist and which remain unchanged and unchange- 

 able under all conditions, whether natural or 

 artificial, hitherto known to us it follows that 

 the speculation that they may be indefinitely 

 altered, or that new units may be generated under 

 conditions yet to be discovered, is perfectly legiti- 

 mate. Theoretically, at any rate, the transmut- 

 ability of the elements is a verifiable scientific 

 hypothesis; and such inquiries as those which 

 have been set afoot, into the possible dissociative 

 action of the great heat of the sun upon our 

 elements, are not only legitimate, but are likely 

 to yield results which, whether affirmative or 

 negative, will be of great importance. The idea 

 that atoms are absolutely ingenerable and im- 

 mutable " manufactured articles " stands on the 

 same sort of foundation as the idea that biological 

 species are " manufactured articles " stood thirty 

 years ago; and the supposed constancy of the 

 elementary atoms, during the enormous lapse of 

 time measured by the existence of our universe, 

 is of no more weight against the possibility of 

 change in them, in the infinity of antecedent 

 time, than the constancy of species in Egypt, 

 since the . days of Rameses or of Cheops, is 

 evidence of their immutability during all past 

 epochs of the earth's history. It seems safe to 



