THE MOUNT DESERT EEGION 11 



on no area of this size have I seen growing together forests 

 representing such ditferent conditions and consequently with 

 such different requirements. The vegetation in general ap- 

 pears to be even more remarkable than the forests. Rand 

 has found on the Island 230 species of plants common to the 

 arctic. The crowberry (Empetrum mgrum) grows here at 

 sea level, while inland at this latitude and even further north 

 it is found only on the summits of the high mountains above 

 timber line under truly arctic alpine conditions, and still the 

 southern sweet fern {Myrica asplenifolia) grows here in 

 actual contact with these boreal plants. 



''An indication of the comparative mildness of the Mt. 

 Desert climate in spite of its arctic flora, is to be found in a 

 group of Japanese pines growing at one of the gateways 

 north of the village of Bar Harbor, a tree so sensitive to cold 

 that it is killed at the latitude of New York, which yet has 

 lived on this island for twenty years without protection in 

 Avinter. ' ' 



In the remarks by Rand and Redfield on the plant distribu- 

 tion you will notice that an exception is made of the maritime 

 flora, otherwise there is a "resemblance to the general flora 

 of the White Mountain region." This is, to a large degree, 

 equally true of the insects. The same trees and plants of 

 the two places have the same insect enemies, and these insects 

 in turn serve as hosts for the same parasites. The elevations 

 of the island are not sufficient for the arctic-alpine forms of 

 Mount Washington and the boreal species are more com- 

 monly found near the shores and in the vicinity of the lakes, 

 cold spring runs, and bogs, the more sheltered and southern 

 exposures probably harboring the greater number of austral 

 species. 



In regard to the distribution of aquatic insects, as pointed 

 out by Dr. R. H. Howe, Jr.,^ cold bogs and ponds that are 

 spring fed have less extremes in temperature than ponds that 

 are not thus supplied with water. Thus he found boreal and 



* ' ' The distribution of New England Odonata. ' ' Proe. Boston Soc. Nat. Hist., 

 vol. 36, p. 110, 1921. 



