LIFE: ITS NATUEE, ORIGIN AND MAINTENANCE 15 



words, to a process of gradual evolution.* But it has been customary of 

 late amongst biologists to shelve the investigation of the mode of origin 

 of life by evolution from non-living matter by relegating its solution to 

 some former condition of the earth's history, when, it is assumed, oppor- 

 tunities were accidentally favourable for the passage of inanimate matter 

 into animate ; such opportunities, it is also assumed, having never since 

 recurred and being never likely to recur, f 



Various eminent scientific men have even supposed that life has not 

 actually originated upon our globe, but has been brought to it from 

 another planet or from another stellar system. Some of my audience 

 may still remember the controversy that was excited when the theory of 

 the origin of terrestrial life by the intermediation of a meteorite was 

 propounded by Sir William Thomson in his Presidential Address at the 

 meeting of this Association in Edinburgh in 1871. To this ' meteorite ' 

 theory J the apparently fatal objection was raised that it would take 

 some sixty million years for a meteorite to travel from the nearest stellar 

 system to our earth, and it is inconceivable that any kind of life could 

 be maintained during such a period. Even from the nearest planet 

 150 years would be necessary, and the heating of the meteorite in 

 passing through our atmosphere and at its impact with the earth would, 

 in all probability, destroy any life which might have existed within it. 

 A cognate theory, that of cosmic panspermia, assumes that life may exist 

 and may have existed indefinitely in cosmic dust in the interstellar spaces 

 (Bichter, 1865 ; Cohn, 1872), and may with this dust fall slowly to the 

 earth without undergoing the heating which is experienced by a meteorite. 

 Arrhenius, who adopts this theory, states that if living germs were 

 carried through the ether by luminous and other radiations the time 

 necessary for their transportation from our globe to the nearest stellar 

 system would be only nine thousand years, and to Mars only twenty 

 days ! 



But the acceptance of such theories of the arrival of life on the earth 

 does not bring us any nearer to a conception of its actual mode of origin ; 

 on the contrary it merely serves to banish the investigation of the question 

 to some conveniently inaccessible corner of the universe and leaves us in 

 the unsatisfactory position of affirming not only that we have no know- 



* The arguments in favour of this proposition have been arrayed by Meldola in his 

 Herbert Spencer Lecture, 1910, pp. 16-24. Meldola leaves the question open whether 

 such evolution has occurred only in past years or is also taking place now. He con- 

 cludes that whereas -certain carbon compounds have survived by reason of possessing 

 extreme stability, others the precursors of living matter survived owing to the 

 possession of extreme lability and adaptability to variable conditions of environment. 

 A similar suggestion was previously made by Lockyer, Inorganic Evolution, 1900, 

 pp. 169, 170. 



f T. H. Huxley, Presidential Address, 1870 ; A. B. Macallum, ' On the Origin of 

 Life on the Globe,' in Trans. Canadian Institute, VIII. 



| First suggested, according to Dastre, by de Salles-Guyon (Dastre, op. cit., p. 252). 

 The theory received the support of Helmholtz. 



Worlds in the Making, transl. by H. Borns, chap, viii., p. 221, 1908. 



