254 PRACTICAL COURSE IN BOTANY 



for instance, in producing tubers or in growing bulbs, — 

 it is apt to bear few seeds and to depend more or less com- 

 pletel}' upon other methods of reproduction. 



Among cultivated plants, selection on the part of man, 

 whether conscious or unconscious, has perhaps contributed 

 more than any other cause to bring about the same result. 

 To this agency is probably due the development of our com- 

 mon domestic fig, of which over four hundred varieties that 

 mature fruits without fertilization are cultivated in the United 

 States alone. The fig was one of the earliest fruits known to 

 cultivation; and the early navigators, ignorant of the processes 

 of fertilization, would naturally, in choosing specimens to 

 carry home with them, select only fruit-bearing trees. Such 

 of these as matured fruits would be preserved and propagated, 

 until, by repeated selection, hundreds of edible varieties have 

 been developed that ripen fruits without caprification (279) . 



287. The use of the fruit to the plant. — The object of 

 the fruit is to furnish protection to the seeds during their 

 period of development and inactivity, and to aid in various 

 ways the work of dispersal. It probably takes part also in 

 digesting and diffusing nourishment for the use of the develop- 

 ing seeds. It has been shown in previous chapters that plants, 

 almost without exception, are in the habit of storing up 

 food in various ways as a provision for fruiting. That a 

 large portion of the stored nourishment is used up in the per- 

 formance of this function is proved by its disappearance from 

 those parts — for example, from fleshy roots, such as beets 

 and turnips, after they have " gone to seed." 



Practical Questions 



1 . What is the use of the down on the peach ? The bloom of the plum 

 and grape? [202, (1); Exp. 91.] 



2. Why are apples, pears, plums, and other fleshy fruits nearly always 

 rosier on one side than on the other? (Exp. 90.) 



3. Can annuals be improved in any other waj^ than by seed selec- 

 tion? 



4. Would a seedless annual be perpetuated under natural conditions ? 



