194 NATURE STUDY. 



would enable the plant to exert to the utmost its lifting 

 powers. In describing the preliminary experiments and 

 the theories on which they based their plans, Mr. Clark 

 says : 



"The following considerations suggested the idea: 

 First — It is a well known fact that beans, acorns and other 

 seeds often lift comparatively heavy masses of earth in 

 forcing their way up to the light in the process of germi- 

 nation. Secondly — We have all heard how common mush- 

 rooms have displaced flagging stones manj^ j^ears since in 

 Batingstoke, and more recently in Worcester, England. 

 In the latter case, only a few \veeks ago, a gentleman, 

 noticing that a stone in a walk near his residence had been 

 disturbed, went for the police, under the impression that 

 burglars were preparing some plot agaipst him. Upon 

 turning up the stone, which weighed eighty pounds, the 

 rogues were discovered in the shape of three giant mush- 

 rooms. Thirdly — Bricks and stones are often displaced 

 by the growth of the roots of shade trees in streets. Cel- 

 lar and other walls are also frequently injured in a similar 

 way. Fourthly — There is a common belief that the grow- 

 ing roots of trees frequentl}^ rend asunder rocks, on which 

 they stand, by penetrating and expanding within their 

 crevices. 



" Having never heard of any attempt to measure the ex- 

 pansive force of a growing plant, we determined to experi- 

 ment in this direction. At first we thought of tr5dng the 

 expansive force of some small, hard, green fruit, such as 

 a hickory nut or a pear, but the expansion was so slow 

 and the attachment of the fruit to the tree so fragile that 

 the idea was abandoned. The squash, growing on the 

 ground, with great rapidity and to an enormous size, seem- 

 ed, on the whole, the best fruit for the experiment. 



" Accordingly, seeds of the mammoth yellow Chili hav- 

 ing been obtained, they were planted in the propagating 



