THE VIOLET. THE PRIMROSE. 



27 



have been termed by Dr. Kuhn, are already known to 

 exist in about fifty genera. Their object probably" is to 

 secure, with as little expenditure as possible, the con- 

 tinuance of the species, in cases when, from unfavourable 

 weather or other causes, insects are absent ; and under 

 such circumstances, as scent, honey, and color are of no 

 use, it is an advantage to the plant to be spared from 

 the effort of their production. 



As the type of another class of cases in which two 

 kinds of flowers are produced by the same species (though 

 not on the same stock) we may take our common Cow- 

 slips and Primroses. If you examine a number of them, 

 you will find that they fall into two distinct series. In 

 some of the flowers, the pistil is as long as the tube, and 

 the button-shaped stigma (Fig. 29, st) is situated at the 

 month of the flower ; the stamens (a a) being half-way 

 down the tube : while in the other set, on the contrary, 



CO 



ooOO 

 



X 250 



FIG. 29. Primula (long-styled form). FIG. 30. Primula (short styled form). 



the anthers are at the mouth of the flower, and the 

 stigma half-way down. The existence of these two 

 kinds of flowers had long been known, but it remained 

 unexplained until Mr. Darwin devoted his attention to 

 the subject. Now that he has furnished us with the 

 clue, the case is clear enough. 



