SUMMARY OF RESULTS. 
1457 
and at a latitude of 82° N. in the Arctic.^ The surface temperature of the sea could not Temperature 
well have been less than about 70° F., and the same temperature and the same marine 
fauna prevailed from equator to poles, the temperature not being higher at the equator. Period. 
Flowering plants did not exist in tlie coal period. Flowers with vivid and brilliant tints 
only appeared in Mesozoic ages when for the first time the sun pierced the envelope of 
dense clouds that surrounded the whole earth. The atmosphere was less agitated then than 
now. In early Mesozoic times cooling at the poles and differentiation into zones of 
climate appear to have commenced, and temperature conditions did not afterwards admit of 
coral reefs in the polar area. But the colder and hence denser water that in consequence 
descended to the greater depths of the ocean carried with it a large supply of oxygen, 
and life in the deep sea became possible for the first time, There have been many 
speculations as to how a nearly uniform temperature could have been brought about 
in sea- water over the whole surface of the earth in early geological ages, as well as 
to how sufiicient light could have been present at the poles to permit of the luxuriant 
vegetation that once flourished in these regions. The explanation that appears to me 
the most satisfactory is the one which attributes these conditions to the very much 
greater size of the sun in the early stages of the earth’s history — an idea first intro- 
duced into geological speculations by Blandet,^ who likewise discussed the relations 
of Arctic and Antarctic faunas — together with the greater amount of aqueous vapour in 
the atmosphere and the greater mass of the atmosphere. 
The pelagic Algse, Kadiolaria, and Foraminifera above referred to are probably the 
but slightly modified descendants of a very ancient universal pelagic fauna and flora. 
Life in its simplest form most likely first appeared in Pre-Cambrian times in the 
detrital matters laid down about the mud-line, when the mud-line was generally not so 
deep, and the land-surfaces were more extensive than at the present time. From these 
simple forms, which would occasionally be carried into the superincumbent waters, 
the pelagic Protophyta and Protozoa, which peopled the surface-waters of the Pre- 
Cambrian ocean, were most probably derived. Kadiolaria, and possibly also pelagic 
Foraminifera, have been discovered in Pre-Cambrian rocks.^ From their remains being 
preserved in these rocks we may suppose that the Kadiolaria were then even more Flora of the 
abundant than in modern seas, and their skeletons appear likewise to have been more Pre-Cambrian 
massive. Kadiolaria and other silica-secreting organisms are much more abundant in 
those parts of the present ocean where there is a low salinity and where the surface is 
frequently affected by fresh water bearing the finest clayey matter in suspension. Me 
have thus then a hint that the waters of the Pre-Cambrian ocean were probably not so 
1 Lapparent, Traite de Geologic, ed. 3, Paris, 1893, p. 884. 
2 Bull. Soc. Geol. de France, ser. 2, t. 25, p. 777, 1867-8. 
2 L. Cayeux, Sur la presence de restes de Foraminiferes dans les terrains precambrian de Bretagne, Comptes Rendm, 
tom. cxviii., p. 1433, 1894. 
