336 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1911. 



to conclude that the cycadophyta of the past have always flourished 

 under similar conditions. On the contrary, we must admit that dur- 

 ing the Mesozoic period, when these plants were abundant, it would 

 no doubt have been possible to find several species which had adapted 

 themselves to an Alpine climate if such a one had then existed. And 

 if, since then, the differentiation of climates has begun to make itself 

 felt, it would be again a case of overlooking the creative power of 

 life if we assumed that none of the species of cycadophytes were 

 able to adapt themselves to a temperate climate in the Polar regions. 

 Again we meet with difficulties, even when we study the plants of 

 the Tertiary period, which are assigned to genera still living. Our 

 common juniper (Juniperus communis, Linn.), which exists in 

 northern Europe as far north as the North Cape, exceeds by 20 to 25 

 degrees of latitude, in the Eastern Hemisphere, the northern limit, 

 not only of the other species of this genus, but also the whole family 

 of the cupressinese. Now, if one imagined that the common juniper 

 were extinct, one would naturally draw conclusions relative to the 

 fossil remains from the distribution of the other species, and one 

 would consequently suppose that it lived under a climate much 

 warmer than is actually the case. One would scarcely imagine that 

 we were concerned with a plant adapted not only to temperate but 

 also to Arctic climates. (One finds the juniper, on the western side 

 of Greenland, up to the sixty-fourth parallel.) 



These examples counsel prudence, and the matter should be treated 

 with judgment and circumspection. But, even if it is necessary to 

 make reservations, when one seeks to determine from the fossil plants 

 the nature of the former climates in the Arctic regions, at least one 

 can not doubt that they were distinctly warmer than that of the 

 present day. The difficulty of explaining these former climates, 

 especially when one has to take into consideration the length of the 

 winter night, is without doubt the reason which has led some scientists 

 to evade the question, instead of seeking to solve it. It is indeed a 

 case of evading the question when it is boldly asserted that the plant- 

 remains, on which Heer * has based his theories of ancient Arctic 

 climates, have been drifted by marine currents to the places where 

 they have been found. 



It is not to be disputed that plant debris may be transported in 

 water for a very great distance without being damaged, provided that 

 they are carried at a sufficient depth to escape the influence of the 

 movements of the surface layers of the water. When Agassiz was 

 engaged in dredging on the American coasts, he found that the bottom 

 of the sea — sometimes to a depth of nearly 3,000 meters — was covered 

 with plant debris, such as wood, branches, leaves, seeds, and fruits, 



i O. Heer, Flora fossilis arctica, vols. 1-7, Zurich, 1868-1883. 



