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THE AMERICAN NATURALIST [Vol. LVI 



have found the conditions requisite to their growth and 

 further development. 



It seems, on careful deliberation, that strong arg-uments 

 may be brought forward for both the theory that single- 

 celled green algae and the theory that bacteria were the 

 primordial organisms, if we consider merely the argu- 

 ments which enter into the usual discussions of the sub- 

 ject. But it appears to me that we must penetrate beyond 

 what is ordinarily called careful deliberation, if we would 

 see other possibilities for explaining the origin of living 

 matter. There is no logical reason for confining our 

 attention in these discussions to the single-celled algae 

 and the bacteria which we know. There are, in addition, 

 bacteria so small as to challenge and defy our ingenuity 

 for devising means for rendering them visible. What 

 may not further discoveries about their nature and re- 

 quirements for life unearth for us which may be of the 

 most vital significance to the solution of our problem! I 

 have tried in imagination to go beyond, far beyond, the 

 ultramicroscopic bacteria and have pictured to myself the 

 following condition for the origin of living matter: A 

 single molecule of organic matter, let us say, a polypeptid 

 or a proteid molecule produced by the force which I have 

 discussed, exerted as chemical energy, may, in floating 

 about in its aqueous medium on the earth's surface, sud- 

 denly find itself in a field of radioactive 'force or some 

 similar force which causes its atoms to orient themselves 

 in such fashion and to vibrate in such a manner as to 

 endow it with certain activities which we now regard as 

 attributes of life. Crude though this conception may be, 

 it constitutes a step, though perhaps a very bold one, into 

 the realm of possibilities for explaining the origin of the 

 first living cell, a subject which we must consider together 

 with all our theories of evolution if we do not wish to 

 remove the inspiration to progress by ;iii"niivu at an 

 impasse in our theories and our hypotlu'sc^. 



In conclusion, it is well to review briefly tlie dix-ussion 

 which I have just presented in a very brief form. Out 



