Trans. N. V. Ac. Sci. 96 April 14, 



dant growth of corals. There is no evidence that a high temperature 

 was required to produce these coral masses. It was true that the 

 corals were aggregated together in such a way as to imply a luxuri- 

 ant growth, and that, at the present day, all the evidence tends to 

 show that reef-building requires a warm climate. It was found that, 

 on the land nearest to the coral-reefs of the Devonian seas, tree- 

 ferns grew, which were of as large size as any now growing in the 

 tropics. 



Since Paleozoic times and the formation of the present topo- 

 graphical features and the interruptions of the great oceanic current, 

 the changes which have occurred may indicate cosmical interfer- 

 ences of some kind. In conclusion, he would only suggest that the 

 problem was very complicated and required the consideration of many 

 facts. 



Prof. Warring stated that the view he had offered did not indicate 

 a uniformity of climate over the twelve months. He had wished to 

 direct attention merely to the absence of the changes of the seasons 

 in former geological periods. 



The President remarked that the alternations of temperature on 

 this continent often reached 100° of Fahrenheit or more at the same 

 locality during a single year. This indicated the endurance by our 

 vegetation of a great range in changes of temperature. In our winter 

 the temperature often drops 25° in a few days. This was a greater 

 trial to the vitality of a plant than a steady cold. He could not 

 imagine that the economy of plants would be greatly affected by polar 

 conditions. 



Prof. Hubbard remarked on the wide variations in temperature 

 which frequently occurred in the latitude of Boston, sometimes 

 amounting to 142° at that city. 



Prof. Warring called attention to the peculiar kinds of plants 

 which thrived in Miocene and earlier times. Their fellows in tropical 

 latitudes, at the present day, were very sensitive to changes of tem- 

 perature. So far as concerned the doctrine of environment, how 

 could plants so entirely unlike have been developed under such differ- 

 ent conditions ? 



The President pointed out that some plants of the northern 

 Tertiary have even now a wide range ; thus, the Sweet Gum, though 

 found over our continent, is far more abundant in Louisiana. The 

 Sassafras has also a very wide range, extending from Canada to the 

 Southern States, even into Texas. The Magnolias, which are found 

 in the fossil state, are not identical with the species of the present 

 day ; but the modern species, the cucumber tree, has now a wide range. 

 There were vast numbers of plants in the Tertiary of the Arctic which 



