. Popular science monthly. lowlybut constantly lifting this enormous weight. The fissure is at an ? 1 ulmA <ir-~ . ?? im \dT i^m^k ftMk $£&& »^fe~/. b-iLJv . ._,. ssi— j* /Vr * . ? ^jU*&t %t ~ f£5t9^ * - ^T^ ^^0^t w^^^^r wfiS 1 of jj \^^.. C* jf^^^^k fc-^. ? ? N % J. *. ^< ^^^Hfl y^ fetT^N^. —<sji_ MH^a Vv ^ ^_:— r^P1 X. Fig. 1. Showing large black birch (Betula lenta L.), one of whose rootsis lifting an 18-ton boulder. 232 THE POPULAR SCIENCE MONTHLY angle of about 15 degrees. The vertical diameter of the root where itenters is only 4 or 5 inches, while its lateral diame
. Popular science monthly. lowlybut constantly lifting this enormous weight. The fissure is at an ? 1 ulmA <ir-~ . ?? im \dT i^m^k ftMk $£&& »^fe~/. b-iLJv . ._,. ssi— j* /Vr * . ? ^jU*&t %t ~ f£5t9^ * - ^T^ ^^0^t w^^^^r wfiS 1 of jj \^^.. C* jf^^^^k fc-^. ? ? N % J. *. ^< ^^^Hfl y^ fetT^N^. —<sji_ MH^a Vv ^ ^_:— r^P1 X. Fig. 1. Showing large black birch (Betula lenta L.), one of whose rootsis lifting an 18-ton boulder. 232 THE POPULAR SCIENCE MONTHLY angle of about 15 degrees. The vertical diameter of the root where itenters is only 4 or 5 inches, while its lateral diameter, owing to com-pression, is 18 or 20 inches, or more. Careful measurements and specific gravity determinations wouldindicate that the weight of the boulder is about 18 tons, and this isannually being lifted higher and higher by the root growing in thecrack. The roots of trees often penetrate, and, as they grow, displace thefoundation walls of buildings. We recall an old, heavy-timbered. *s Fig. 2. Showing mushroom rupturing concrete. colonial house which had one corner thrown considerably out of thevertical by the growth of tree roots under the foundation. In this casethe roots must have lifted many tons in weight. In another instancea gentleman noticed that the stone in a walk leading to his residencehad been displaced. He became alarmed and sent for the police, labor-ing under the impression that burglars were responsible for the dis-placement and were planning some deep plot against him. But onmoving the stone, which weighed 80 pounds, three large mushroomswere discovered and the mischief was explained. Instances are knownof mushrooms pushing up through hard tar walks two or three inchesthick without the slightest difficulty or evidence of injury to their deli- THE POWER OF GROWTH IN PLANTS 233 cate tissues; and even seedlings often displace comparatively largemasses of soil in pushing up through. For several years we have been observing the rupturing of veryhard
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