C. B. WAHHINi;. 101 



to flow, yet in Spitsbergen — one of a group of not large 

 islands surrounded by a broad expanse of water — the 

 cold is very intense. The capacity of water for heat 

 has not changed, — did the Gulf Stream, or the Japan 

 Current, in geological times have a greater flow than at 

 present \ The effective cause of these streams is the 

 difference between high and low latitude temperature. 

 If this difference was nothing, there would be no cur- 

 rents, and the less the difference the less the currents. 

 In geological times the difference must have been small 

 for the same plants and animals lived from the tropics, 

 if not from the equator, to as near the pole as has been 

 explored. Hence the flow of these currents must, to say 

 the least, have been no greater than at present. 



But it may be said that some change in the arrange- 

 ment of the land caused a change in the direction of the 

 current. It is now generally admitted that the outlines 

 of the continents are the same as they were from the be- 

 ginning. If this is true, there has been no great change 

 in the direction of the ocean currents. Moreover, the 

 eastward trend of the Gulf Stream is due to the rotation 

 of the earth on its axis ; hence, it would not, in any 

 case, flow up Baffin's Bay ; and, therefore, the warmth 

 of Disco Island must be accounted for in some other 

 way. If it be said that the Japan current flowed 

 through a wider and deeper channel into the Arctic 

 Ocean, there must have been some way of keeping it 

 warm while slowly coursing several thousand miles 

 around the northern shores of North America. As the 

 same plants and animals lived in arctic regions, lat. 81° 

 40', and well down toward the equator, it would seem 

 that climatic conditions could not have been affected by 

 enormous differences in the length of their days and 

 nights, or, in other words, that the nights there were 

 not as they are now. 



The influence of light, or actinic force, on plants is very 



53 



