270 ELEMENTARY BIOLOGY 



On the stems of most plants many more buds are produced 

 than ordinarily develop. But an injury or a mutilation will bring 

 about the development of some of the resting buds. If we cut into 

 the stem of a tall india-rubber plant, close to one of the nodes, we 

 can induce the nearest bud to swell up and begin developing. In 

 this way we can to a certain extent regulate the form of the plant, 

 by determining where branching is to take place (Fig. 109). 



FIG. 108. Regeneration in lizard 



The glass snake and other lizards throw or cut off a part of the body when attacked, 

 and later regrow the lost tail or limb. The original tail of the lizard is an extension 

 of the backbone ; in the regenerated tail there are no vertebrae. Experimentally lizards 

 have been made to regenerate two or three tails in succession. The figure shows the 



Surinam Ameiva 



323. Grafting. Suppose we have a vigorous apple tree that 

 is perfectly healthy and satisfactory in every way, except that 

 its fruit is too hard or too small or too sour. We have no 

 way of making the fruit of that tree of a better quality. But 

 we can use the vigorous roots of that tree, and the food- 

 making factories (the leaves), to supply water, salts, and food 

 to a twig from another tree that bears the kind of apples we 

 like (see Fig. no). A notch is cut in one of the branches of 

 the first tree, and the wedge-shaped butt of the twig from the 

 second tree is fitted into the notch. The joint is covered with 

 a special wax preparation to keep out fungi and bacteria and 



