l60 HEREDITY AND EVOLUTION IN PLANTS 



nearest rock thereby gaining warmth, which enables them 

 to exist in spite of tempest and cold. These in their 

 turn give place to the Greenland sandwort, the diapensia 

 (Fig. 75), the cassiope, and others, with arctic rushes, 

 sedges, and Uchens, which flourish on the very summit."^ 



According to Flint, there are about fifty strictly alpine 

 species on these summits, found nowhere else in New 

 England and New York, except on similar summits, such 

 as Mt. Katahdin in Maine, and Mt. Marcy and Mt. 

 Mclntyre in New York State. 



Incidentally, it may be remarked that a similar state- 

 ment may be made for the animal life. Writing of the 

 insects, Scudder says^ that, "in ascending Mt. Washing- 

 ton, we pass, as it were, from New Hampshire to northern 

 Labrador; on leaving the forests we first come upon animals 

 recalling those of the northern shores of the Gulf of St. 

 Lawrence and the coast of Labrador opposite Newfound- 

 land; and when we have attained the summit, we find 

 insects which represent the fauna of Atlantic Labrador 

 and the southern extremity of Greenland." 



118. Effects of Continental Glaciation. — The above 

 mentioned and other similar cases of discontinuity are 

 satisfactorily explained by the advance and retreat of the 



1 Among numerous species that have been recorded from both Labra- 

 dor and the peaks of the White Mountains, there may be mentioned the 

 following: Salix argyrocarpa, S. phylicifolia, S. herbacea, S. uva-ursi, 

 Comandra limda, Arenaria groenlaniUca, Silene acaulis, Oxyria digyna, 

 Cardamine bellidifoUa laxa, Saxifraga rivularis, Sibhaldia procunibens, 

 Empetrum nigrum, Epilobium Hornemannii, Loiseleuria procumbens, 

 Rhododendron Lapponicum, Phyllodoce coerulea, Cassiope hypnoides, 

 Arctostapphylos alpina, Vaccinium coespitosum, Diapensia Lapponica, 

 Veronica alpina var. unalaschensis, Gnaphalium supinum. 



' Scudder, Samuel H. Distribution of insects in New Hampshire. In 

 Hitchcock, C. H. The geology of New Hampshire, i :34i. 1874. 



