PRESIDENT'S ADDRESS. Ixvii. 



sure to throw light upon the conditions of organic life in the polar 

 seas and the polar regions. It is remarkable that all the members 

 of the expedition kept well and fit for work during the whole 

 of the duration of the expedition. 



The great summary of the Challenger Expedition by Dr. 

 Murray was published last year, enriched with notes of his own 

 journal, based on the log and the official reports. It deals with 

 the history of oceanography. It may be as well to make an 

 extract dealing with his speculative views on the influence of 

 climate in the distribution of life. Beginning with the strong 

 resemblance between the north and south polar marine faunas, 

 and the general absence of similar forms in the intervening belt 

 the author says, "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, 

 descending to the greater depths of the ocean, carried with it a large 

 supply of oxygen, and life in the deep seas 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 sufficient light could have been present at the Poles to 

 permit of the luxuriant vegetation that once flourished in those 

 regions. The explanation which appeared to be the most satis- 

 factory to Dr. Murray was that which attributes these conditions 

 to the greater size of the sun in the early stages of the earth's 

 history, together with the greater amount of aqueous vapour in the 

 atmosphere." He proceeds " The pelagic algae, radiolaria, and 

 foraminifera are probably but slightly modified descendants of a 

 very ancient, universal pelagic fauna and flora. Life in its 

 simplest form most likely appeared in pre-Cambrian times in 

 the detrital matters laid down about the mud-line (which Dr. 

 Murray limits to 100 fathoms, and considers to indicate usually 

 the edge of the oceanic continental slope), when the land surfaces 

 were more extensive than they are at present. 



