in.] CHARACTERS. 27 



membrane of the embryo-sac itself. This new cell by 

 repeated division ultimately develops into the embryo. At 

 the same time, in the lower portion of the embryo-sac, an 

 indefinite number of minute cells, originating usually in 

 the same manner, lay the foundation of the albumen, which 

 in the buttercup acquires, and permanently maintains, a 

 relatively large bulk as compared with the embryo, and the 

 ovule then becomes the young seed. 



5. We can now understand why the petals and stamens are 

 deciduous. Their function is soon accomplished, and their 

 texture is too delicate to allow them to persist, although the 

 calyx of the Orange, from its firmer texture, remains until 

 the fruit becomes ripe. A calyx or corolla remaining thus 

 attached after the time of flowering is said to be persistent. 



6. From what we have here described of the functions of 

 the different organs of tlie flower, the high importance to 

 the plant of their proper performance must be plain. And 

 from the general constancy which the parts of flowers 

 present in their principal features, both in the structure of 

 the several parts and in their relations to each other, in 

 groups of plants which from numerous general resemblances 

 we may reasonably imagine to be related by descent (that is, 

 related to each other in the same way that Europeans are 

 more nearly related to each other than they are to the Negro 

 or Indian races, or as fish are more nearly related to each 

 other than they are to birds or reptiles), botanists make use 

 of characters afforded by the organs of the flower and fruit 

 to mark, in words, the principal divisions of the vegetable 

 kingdom. Hence it is desirable, before we proceed to 

 consider the organs which are more subject to variation, 

 that we should acquire a correct notion of the nature of 

 the principal modifications to which the parts of the flower 

 are liable in different plants. 



