PRESIDENT’S ADDRESS. 13 
supernatural intervention in the first production of life, we are not only 
justified in believing, but compelled to believe, that living 
Life a pro- matter must have owed its origin to causes similar in 
“eg evo- character to those which have been instrumental in pro- 
ducing all other forms of matter in the universe; in other 
-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, 
opportunities 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.*® 
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 ‘ mete- 
orite ’ theory 14 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 (Richter, 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! 
12 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 concludes 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. 
13-T. H. Huxley, Presidential Address, 1870; A. B. Macallum, ‘On the 
Origin of Life on the Globe,’ in Trans. Canadian Institute, VIII. 
M4 First suggested, according to Dastre, by de Salles-Guyon (Dastre, op. cit., 
-p. 252). The theory received the support of Helmholtz. 
18 Worlds in the Making, transl. by H. Borns, chap. viii., p. 221, 1908. 
