104 Forty-second Annual Report on the 



times cross each other at various angles, and thus present a 

 curious and somewhat artificial aspect. In a few boggy places 

 the cranberry, Vaccinium macrocarjjum, was growing. 



The summit of the mountain is somewhat isolated and is 

 exposed to sweeping winds from every direction. This, together 

 with an altitude of 2,000 feet or more, and a very thin soil, must 

 render the place a trying one for all except the most hardy species 

 of plants. There is a marked tendency to dwarf development. 

 The pitch pines have a starved misshapen appearance and bear 

 cones when but one or two feet high. Specimens of chokeberry 

 but eight or ten inches high were in fruit ; also, the shad bush at 

 two feet and the mountain holly at one foot. The narrow-leaved 

 variety of the dwarf blueberry bore fruit though but three or four 

 inches high. The coldness of the station is indicated by the 

 presence of species usually found in more northern latitudes or in 

 more elevated places. The rhodora already mentioned, the trifid 

 rush, J uncus trifidus, the three-toothed cinquefoil, PotentiUa triden- 

 tata, the slender cotton grass, Eriophorum gracile, and the Green- 

 land sandwort, Arenaria Gh*eenlandica, are examples of this kind. 

 That which is manifestly a principle in nature receives confirma- 

 tion here and is noticed because the existence of such a principle 

 is sometimes overlooked. The principle to which reference is 

 made is that a plant whose strength or vital force has been weak- 

 ened or impaired by any cause, is more liable to suffer from the 

 attacks of parasitic fungi than one whose vigor is unimpaired. 

 The sheep laurel, Kalmia angusti/olia, was badly infested by 

 Dothidella Kalmice, a fungus which attacks the branches of the 

 living plant and causes them to increase in diameter and become 

 blackened. Their leaves do rot attain half their usual size and the 

 branch eventually dies. This fungus is a rare one, and I have 

 never seen vigorous healthy appearing plants affected by it. 

 Rhytisma Canadensis is a more common fungus that attacks the 

 foliage of the mountain holly, but rarely do its attacks equal in 

 severity those on the plants of Sam's Point. This shrub here 

 shows by its dwarf development that the conditions of growth 

 are unfavorable and that its vigor is impaired. Scarcely a 

 clump of the bushes was seen whose leaves were not excess- 

 ively spotted by the blackened swellings of this fungus. The 

 wild black cherry, Prunus serotina, in other places furnishes 

 an illustration of this same principle. On Long Island, in light 



