ORIGIN AND\ DEVELOPMENT OF SOME COMMON FRUITS. 



all these^varjations into account ; for he 

 has learned that in order to raise cer. 

 tain kinds of strawberries, grapes, pears, 

 etc., he must so arrange his plants that ' 

 there shall be a plentiful supply of ripe 

 pollen when the pistils are ready for 

 fertilization. 



What is a flower taken as a whole ? 

 It is a modified branch ; for it has an 

 axis or stem from which grow the parts 

 of the calyx and corolla, these parts 

 being leaves. The stamens and the 

 pistils we belive to be also modified 

 leaves ; for we have many plants like 

 the tulips and white water lily in which 

 the parts of the corolla pass gradually 

 into stamens. This is shown well in 

 Fig. 1520. Moreover, there are many 

 plants in which 

 the pistils de- 

 V e 1 op into 

 leaves instead 

 of taking their 

 ) usual form ; our 

 common tril- 



lium or wake 



Fig. 1520.— White water , . . , 



LILY (Nymphaea odorata), rODin IS One OI 



showing graduation from ^l„__ 



sepal on the left, through mcbc. 



petals to stamens on the 



riRht. If we wish to 



see the origin of a fruit, it is not enough 

 that w^e find in the flower the part from 

 which the fruit comes. We can go still 

 farther back and find the origin of the 

 parts of the flower. If we were to dis- 

 sect a peach bud, or almost any other 

 flower bud in December, we should 

 find all the parts of the flower present in 

 small size. If however, we were to 

 make an examination in August or Sep- 

 tember, we should find the buds then 

 forming. Suppose we dissect carefully 

 the tip of a branch in the late summer ; 

 we should find the appearance shown in 

 Fig. 152 1. The first view shows the 

 apex of the stem directed toward the 

 observer, while growing from it is a circle 



B '■' f 





Fig 1 5Jt.— Development of the Orange Blos- 

 som. (Citrus aurantium). i, tip of stem show- 

 ing the origin of the 5 sepals; 2, the 5 petals 

 beginning to show alternating with the sepals ; 

 3, appearance of the first 5 stamens ; 4, other 

 stamens arising on the flanks of the first 5 ; 5, 

 same stage as the preceding, but in dififerent 

 position, with calyx and corolla cut away ; 6, 

 origin of the circle of pistils as little hoods on 

 the stem ; 7. origin ot pistils showing alone ; 

 8, older stage of stamens and pistils ; 9, 10, it, 

 interior views of pistils : 12, young flower with 

 pistils united into one in the middle, and other 

 parts cut away on the near side ; 13, 14, show- 

 ing the origin of seeds in the pistil; 15, 16, 

 older pistils ; 17, <8, mature flower ; 19, mature 

 pistil ; 20, mature stamen ; 21, ovules in pistil ; 

 22, ovule enlarged. 



of little tongue-like structures. These 

 five tongues are the germs of the five 

 sepals. In No. 2, w^e see the sepals 

 grown longer, while just above, and al- 

 ternating with them are five little eleva- 

 tions, the beginning of the five petals. 

 In No. J, sepals and petals have en- 

 larged, and now appears a third circlet 

 of elevations, the germs of the first 

 stamens. Soon other stamen germs 

 grow out beside these first five, so that 

 in No. 4, S ^nd 6, where calyx and 

 corolla have been partially cut away, 

 one sees a circle composed of many 

 little knobs. In No. 8, still another 

 circle of elevations has risen from the 

 stem, these being hood shaped, and 

 representing the beginning of the circle 

 of pistils. In Nos. 12, ij and /p, these 

 pistil-germs have enlarged and finally 



53 



