28 ZHSSOJV^S WITS PLANTS 



seeing that the apple is the chief concern,— to 

 enable it to develop into a blossom-bud. There is, 

 therefore, a necessary alternation of fruit-bearing 

 buds and non-fruit-bearing buds in the spur of 

 an apple tree. 



26. A twig of Siberian crab apple, taken in 

 spring, is shown in Fig. 25. Year before last, 

 each of the spurs developed a fruit-bud at its 

 summit, and last year each of these spurs bore 

 flowers. The proof of this is seen in the scars 

 left by the flower stems at a a. None of these 

 flowers developed into ripe fruits, otherwise some 

 of the scars would have been much larger than 

 they are. It was probably for that very reason, — 

 the failure of the fruit, — that the spurs were able 

 to throw out leafy shoots nearly or quite an inch 

 long, to continue the growth. Yet, even then, no 

 fruit-bud developed on the ends of these spurs, 

 for the small pointed ends clearly indicate leaf- 

 buds. It is seen, therefore, that there may be an 

 alternation in the fruit-spur, even when the spur 

 does not bear fruit. 



27. An old fruit-spur of a pear tree often 

 looks like that in Fig. 26. One year it grew from 

 the base to a, and there formed a fruit-bud. 

 Let us suppose that this year was 1880. In 1881 

 a pear matured from this bud, as may be seen 

 by a large scar at a. In this year, also, a lat- 



