1883.] NATURAL SCIENCES OF PHILADELPHIA. 195 



Experience of forest growths in the eastern states gave abun- 

 dance of facts, which were quite sufficient to exjjlain the existing 

 state of things, on grounds very different from those assumed by 

 Mr. Muir. Observers knew that there were trees which loved 

 moisture, and trees which preferred dry ground. Swamp-lovers 

 would grow in dry places almost as well as in wet ones, but the 

 dry -lovers would not grow in wet places. The swamp magnolia, 

 swamp willow, swamp azalea, the bald c^qjress, the swamp maple, 

 the sweet gum — every swamp tree that can be named — do just as 

 well, and in man}' cases better, in dr}" ground. This is so well 

 known to every intelligent cultivator of trees, that its correctness 

 is beyond dispute. Here in the east, the largest red ma})les, 

 willows, cypresses, and other swamp trees, aie the occasional 

 specimens which by accident find themselves on dry ground. On 

 the other hand, the dry-land species of pine, oak, maple, and other 

 trees, can under no circumstances be made to grow in wet places; 

 and, theiefore, if Mr. Muir's suggestion that the Sequoia was once 

 a dr^'-land plant, and made the land swampy through its own 

 growth, should b}- any possibility be found correct, it would 

 ])robably be an exceptional case in the vegetable kingdom. It had 

 been shown by himself, the speaker said, in past communications 

 to the Academ}', printed in its Proceedings, that trees only grow 

 in swamps from a provision of nature that their seeds shall only 

 germinate in wet ]jlaces. It seems like a determination of nature 

 that some trees shall grow in swamps, whether they prefer it or 

 not. Though these trees grow better and fruit freely in dry 

 ground, the trees cannot spread, because there is not the moisture 

 required for the seed to grow. 



Mr. Muir mistakes the argument. It is not that sequoias will 

 not grow in dry ground, but that the seed will not germinate to 

 any extent except under highly humid conditions. Ground need 

 not be absolutely wet. The cultivator raises swamp ferns on 

 bricks, and the swamp rhododendron is often found on rocky 

 ledges, but this is onh- where a humid atmosphere keei)S the seed 

 from drying till it grows. The atmospheric humidity at 8000 feet 

 would be more likely to help Sequoia at 8000 feet than at 5000. 

 In concluding this branch of the topic he said the facts spoke for 

 themselves. The seed did not grow now — there were no seed- 

 lings — though seeds were abundant. They grew in former times 

 or the trees would not exist. There must be some change in the 

 conditions necessary to make seeds grow since the forest was 

 started. We know from outside observations that seed of swamp- 

 loving trees will not grow under arid conditions. AVe see that 

 the Sequoia is a swamp-lover. Is not this getting to as close an 

 explanation as science rarely reaches? Ma}'- we not say that 

 Sequoia does not spread because the humid conditions are not as 

 they once were when the forests were founded? This was cer- 

 tainly his conclusion from the i'acts as they presented themselves 

 to his observation. 



