The Orderly Cycles Pursued in Growth 371 



future may embrace wonderful new vegetables or fruits produced 

 by the injection of chemical substances into the young growing 

 tissues of ordinary plants. 



Of somewhat analogous nature are the abnormal growths pro- 

 duced by the presence of parasitic plants. A typical case is found 

 in those remarkable dense growths 

 of many slender upright twigs, 

 found often on Spruce trees and 

 commonly mistaken for nests of 

 big birds. They are generally 

 known as Witches Brooms, and 

 are caused by the presence of a 

 Fungus which sends its nutritive 

 threads into the young growing 

 branch, and seems to produce a 

 paralysis of the delicately-bal- 

 anced controlling power of 

 growth. As a result all the buds 

 in that region proceed to develop, 

 though ordinarily they would 

 mostly be suppressed, and each 

 grows for itself without any ge- 

 otropic correlation with its neigh- 

 bors. Of precisely similar nature 

 are those spiral-radiate-saucer growths on the roots of tropical 

 trees, often sold to tourists as curiosities under the name of 

 ''wooden flowers" (figure 142). Unlike the case of the galls, 

 there is no obvious advantage to the parasite in these methods 

 of growth of its host, and the result seems purely incidental 

 to the paralysis of the regulatory power, — the direction that 

 anarchy takes, as it were, when the hand of the law is re- 

 moved. We see something of the very same sort in the animal 

 world and especially in mankind, in tumors and other abnormal 

 growths, which are likewise a continuation of growth without 



Fig. 142. — A "wooden Huwer" from 

 Guatemala, one-third the natural size. 

 It is explained in the text. 



