NATURAL SCIENCES OF PHILADELPHIA. 353 



but depended on the faA'orable or nnfavorable circumstances under 

 which seeds in certain seasons found themselves. The ascent of 

 Gray's Peak by the way of the Clear Creek Canon afforded an 

 illustration. At the base of the mountain, we find Finns contorta, 

 P. ponderosa, Abies Engelmannii, and a few Abies grandis. As we 

 advance all disappear except Abies Engelmannii, but Pinus aris- 

 tata takes the place of the departed ones. Advancing higher, P. 

 aristata disappears, and only A. Engelmannii is left for the last 

 half mile before reaching the " timber line." The last series of 

 trees appear about fifty years old, even to the boundary line, and 

 then comes perhaps a half mile of Juniperus alpina, Salix arctica, 

 and other small growing things. But on examining this mass of 

 scrubbj' growth, a large quantity of Abies Engelmannii, not more 

 than a couple of feet high, about twenty years of age, and seemingly 

 never to be anj'thing more than scrubs, is found growing with it. 

 An examination of the forests at lower altitudes, however, shows 

 that Abies Engelmannii, even at a thousand feet below, made its 

 first twent}^ or thirty j-ears in a similar scrubby condition. It was 

 no uncommon thing to find specimens of tliis tree perhaps sixty 

 feet or more in height, when clothed with branches to the ground, 

 to have the early branches at the ground still remaining, and in 

 just the same condition as those aliove tlie " timber line." The 

 same thing occurs in American nurseries with some firs. Picea 

 pectinata generally remains in this semi-stunted condition for ten 

 or twenty j-ears, losing its leader annually, spreading its side 

 branches, but increasing its trunk at the ground, and its tap-root 

 in length. After that it ascends rapidly, its leading shoot seldom 

 being destroyed afterwards. He saw no reason, as Gray's Peak 

 was not one of perpetual snow, except perhaps in some of the 

 deepest ravines, why under favorable seasons for germination, 

 Abies Engelmannii might not in time advance towards the top, 

 without regard to any arbitrary " timber line." 



The facts he offered were lie thought worthy of attention by 

 those interested in the geographical distribution of plants. Most 

 forest trees seeded abundantl}' every year, and yet nature seemed to 

 have placed some check on the ultimate perfection of her own great 

 work. And indeed we could see the wisdom of this check ; for if 

 the seeds of these strong forest trees were to grow as readily as 

 the seeds of the smaller annuals, the world, in the absence of man 

 to cultivate, would have its smaller vegetation crowded out, and 

 it would be one vast forest ; and 3'et it seemed an enigma that na- 

 ture should produce such an immense amount of seed with one 

 hand, only to be destroyed b}'^ the otiier, unless we accept this 

 principle, that seed growth is onh' occasional and exceptional to 

 any great extent, and then we see how essential it is always to 

 have a large and fresh stock constantly on hand, as a seedsman 

 would say, so that advantage could be taken of the exceptional 

 conditions when thev occurred. 



