CHAPTER II. 



GENERAL ACCOUNT OF THE EXPERIMENTS. 



THE PEAR FLOWER. 



The flower of tlie pear is regular, perfect, and complete, with its 

 parts iu fives. It has five brownish green sepals; five white, or in the 

 bud usually pinkish petals; twenty stamens; and a five-celled ovary, 

 with five styles and stigmas. The ovary is inferior. In other words, 

 the calyx has its insertion on the top or upper j)art of the ovary. 

 Perhaps the proper way to view the structure is to consider that the 

 ovary is sunken into the expanded end of the stem, and that the latter, 

 with the ovary, develops into the fruit. The so-called fruit is there- 

 fore, as in other members of the pome family, a false fruit. The true 

 fruit — the ripened ovary and its contents — occupies only the central 

 portion of this fruit, as commonly understood, and constitutes perhaps 

 one-fifth of its bulk. This young fruit exists in the flowers with all its 

 parts formed in miniature, except the seeds, which are represented by 

 ovules. Looking at the flower from below, the young, undeveloped pear 

 is plainly discernible; indeed it is easily seen as soon as the buds 

 appear. When viewed from above, the middle of the flower is seen 

 to be occupied by a greenish yellow, saucer-shaj)ed disk, from the 

 center of which, protrude the five styles. The stamens, petals, and 

 sepals are arranged in circles around the outside of this central disk 

 (fig. 1). The styles lead directly down to the ovules, each style ter- 

 minating in a slightly expanded and modified i)ortion, the stigma. 

 This extends a short distance down the inner side of the style and is 

 the organ that receives the pollen. A microscopic examination of the 

 stigma shows its surface to be covered with small, blunt papillae, which 

 form a sort of brush to catch and retain tlie pollen. During at least 

 a part of the life of the flower the stigma secretes a slightly sticky 

 liquid, which moistens its surface. The greenish disk in the center of 

 the flower is the nectary or nectar gland, and here the nectar, or, as it 

 is often erroneously called, the honey of the flower, is secreted. Each 

 cell of the ovary contains two ovules, making ten in all; these when 

 l)roperly fecundated may all develop into seeds, 



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