296 



SCIENCE 



[N. S. Vol. XXXVI. No. 923 



problem which the evolutionary hypothesis 

 offers. 



I assume that the majority of my audi- 

 ence have at least a general idea of the 

 scope of this hypothesis, the general accept- 

 ance of which has within the last sixty 

 years altered the whole aspect not only of 

 biology, but of every other branch of nat- 

 ural science, including astronomy, geology, 

 physics and chemistry. To those who have 

 not this familiarity I would recommend 

 the perusal of a little book by Professor 

 Judd entitled "The Coming of Evolu- 

 tion," which has recently appeared as one 

 of the Cambridge manuals. I know of no 

 similar book in which the subject is as 

 clearly and succinctly treated. Although 

 the author nowhere expresses the opinion 

 that the actual origin of life on the earth 

 has arisen by evolution from non-living 

 matter, it is impossible to read either this 

 or any similar exposition in which the es- 

 sential unity of the evolutionary process is 

 insisted upon without concluding that the 

 origin of life must have been due to the 

 same process, this process being, without 

 exception, continuous, and admitting of no 

 gap at any part of its course. Looking 

 therefore at the evolution of living matter 

 by the light which is shed upon it from the 

 study of the evolution of matter in general, 

 we are led to regard it as having been pro- 

 duced, not by a sudden alteration, whether 

 exerted by natural or supernatural agency, 

 but by a gradual process of change from 

 material which was lifeless, through ma- 

 terial on the borderland between inanimate 

 and animate, to material which has all the 

 characteristics to which we attach the term 

 "life." So far from expecting a sudden 

 leap from an inorganic, or at least an un- 

 organized, into an organic and organized 

 condition, from an entirely inanimate sub- 

 stance to a completely animate state of 

 being, should we not rather expect a grad- 



ual procession of changes from inorganic 

 to organic matter, through stages of grad- 

 ually increasing complexity until material 

 which can be termed living is attained? 

 And in place of looking for the production 

 of fully formed living organisms in her- 

 metically sealed flasks, should we not rather 

 search nature herself, under natural con- 

 ditions, for evidence of the existence, either 

 in the past or in the present, of transi- 

 tional forms between living and non-living 

 matter ? 



The difficulty, nay the impossibility, of 

 obtaining evidence of such evolution from 

 the past history of the globe is obvious. 

 Both the hypothetical transitional material 

 and the living material which was origi- 

 nally evolved from it may, as Macallum has 

 suggested, have taken the form of diffused 

 ultra-microscopic particles of living sub- 

 stance; and even if they were not 

 diffused but aggregated into masses, 

 these masses could have been physically 

 nothing more than colloidal watery slime 

 which would leave no impress upon any 

 geological formation. Myriads of years 

 may have elapsed before some sort of skele- 

 ton in the shape of calcareous or siliceous 

 spicules began to evolve itself, and thus 

 enabled "life," which must already have 

 possessed a prolonged existence, to make 

 any sort of geological record. It follows 

 that in attempting to pursue the evolution 

 of living matter to its beginning in terres- 

 trial history we can only expect to be con- 

 fronted with a blank wall of nescience. 



The problem would appear to be hopeless 

 of ultimate solution, if we are rigidly con- 

 fined to the supposition that the evolution 

 of life has only occurred once in the past 

 history of the globe. But are we justified 

 in assuming that at one period only, and 

 as it were by a fortunate and fortuitous 

 concomitation of substance and circum- 

 stance, living matter became evolved out 



