LIGHT, LUMINARIES AND LIFE. LOM: 
unsuspected by most scientists. A little careful thought enables 
the scientific imagination to see vast possibilities of intimate 
relationship between various elements, under such conditions of 
high temperature and planetary pressure, continued through 
immense periods of time, as are altovether beyond the reach of 
the most powerful laboratory appliances.* 
_For reasons indicated above, and from other considerations, 
we may extend the interval beyond what Lord Kelvin suggests, 
for the early stages of the evolution of life, as it was manifested 
in those early forms, which represent the flora and the fauna of 
our globe down to the Carboniferous Period, when the atmo- 
sphere was by no means so clear as we know it in our experience,t 
and vast forests of vascular cryptoyams (ferns, mosses, lycopods, 
etc.) grew and flourished in the feebly illuminated warm 
atmosphere with such luxuriance as they have never attained 
to since. There would seem to be no valid reason for denying 
that our earth passed through the condition in which the giant 
planet Jupiter appears to exist at present, and gradually 
advanced to those terrestrial conditions, which we know to be 
most favourable to the growth of the higher Cryptogams, so 
luxuriant and abundant in later Paleozoic time; and we may 
fairly contend that the period of time roughly estimated by 
Kelvin since that stage of the earth’s history as 25 millions of 
years, would amply suttice for the further evolution of this globe 
and of the fossilized forms embedded in the strata during the 
Secondary, Tertiary, and Quaternary stages of its history. 
Temporarily and locally such conditions may have partially 
recurred, here and theie, as evidenced by the coal-seams (marked 
however by a different cryptogamous flora) of the Lower 
Keuper of Germany and the Alps, the Lias of Europe and Asia, 
the Dogger, the Wealden, the Cretaceous, and in the Tertiary 
formations, allowance being made for drift-wood as the leading 
material of the Brown Coal. Even at the present time it is 
possible to meet with those dusky and moist conditions favour- 
able to the undergrowth of a sort of “carboniferous” flora, as 
we know from the observations of Hochstetter (quoted by 
Zittelf) in the North Island of New Zealand, and from personal 
observations of my friend Dr. Gybbon Spilsbury in the forest- 
region of the Amazon. 
* Compare Supplementary Note A, to my previous paper to this 
Institute. 
t Except under occasional local conditions, as in a London fog. 
{ Aus der Urzeit, p. 256. 
