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, im the Eastern Hemisphere, the northern limit, 
not only of the other species of this genus, but also the whole family 
of the cupressinee. 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 débris 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 débris, such as wood, branches, leaves, seeds, and fruits, 
10. Heer, Flora fossilis arctica, vols. 1-7, Zurich, 1868-1883. 
