CHAPTEE II. 



Fig. 220. 



SEXUAL GENERATION, AND THE MODE OF ITS 

 ACCOMPLISHMENT: 



SEXUAL generation is performed by two sets of organs, each of which 

 gives origin to a peculiar product, capable of uniting with the other, 

 to produce a new individual. These organs, belonging to the two dif- 

 ferent sexes, are called the male and 

 female organs of generation. The female 

 organs produce a globular body called 

 the egg or germ, which is capable of be- 

 ing developed into the body of the young 

 animal or plant ; the male organs produce 

 a substance which is necessary to fecun- 

 date the germ, and enable it to go througli 

 with the process of growth and develop- 

 ment. 



Such are the essential and universal 

 characters of the organs of generation. 

 These organs, however, while exhibiting 

 everywhere the same principal features, 

 present certain modifications of structure 

 and arrangement in different classes of 

 organized beings. 



In the flowering plants, the blossom, 

 which is the generative apparatus (Fig. 

 220), consists first of a female organ con- 

 taining the germ (a), situated usually 

 upon the highest part of the leaf-bearing 

 stalk. This is surmounted by a nearly 

 straight column, termed the pistil (6), dilated at its summit into a 

 globular expansion, and occupying the centre of the flower. Around it 

 are arranged several slender filaments, or stamens, bearing upon their 

 extremities the male organs, or anthers (c, c). The whole is surrounded 

 by a circle or crown of delicate colored leaves, termed the corolla (d), 

 which is frequently provided with a smaller sheath of green leaves out- 

 side, called the calyx (e). The anthers, when arrived at maturity, dis- 

 charge a fine organic dust, called the pollen, the grains of which are 

 caught upon the extremity of the pistil. Each pollen-grain then absorbs 

 the nutritious juices with which it is in contact, and develops from its 

 substance a tubular prolongation, the pollen-tube, which, by its con- 

 ( 682 ) 



BLOSSOM OP IPOM<EA PUK- 

 PTJREA. (Morning-glory.) a. Germ. 

 6. Pistil, c. c. Stamens, with anthers. 

 d. Corolla, e. Calyx. 



