STRUCTURE OF THE PLANT 



21 



FIG. ii. 



to refer to abnormal plants to see the leaf-like character 

 of the carpel and the resultant fruit. It is enough to 

 glance at the fruit of a legu- 

 minous plant, such as a bean, 

 or still better the fruit of the 

 peony, to be convinced that 

 it is nothing but a leaf, the 

 edges of which have curved 

 over and grown together, thus 

 forming an organ with a longi- 

 tudinal join (suture) with a 

 hollow space inside. In other 

 cases the ripe fruit in bursting 

 shows quite clearly that it con- 

 sists of several little leaves 

 grown together at their edges. 



The carpel, then, has been derived from one or more 

 little leaves modified in form. But not in all ab- 

 normal flowers are the carpels transformed into real 

 leaves as we see it in the cherry. In other cases the 

 carpel transforms itself into organs more closely related 

 to it, such as stamens and petals. The transforma- 

 tion of a pistil into a stamen can sometimes be 

 studied in the flower of a willow. Occasionally bright 

 red petals can be found in the centre of double 

 peonies with white, shiny ovules on their edges. These 

 are surely carpels which have become transformed into 

 petals, but which have kept their ovules. It follows 

 that a pistil can transform itself into all the preceding 

 organs, i.e. into stamens, petals, and real green leaves. 

 Does not this prove that all these organs are of one and 

 the same origin ? 



In our analysis of the plant we have reached its 

 topmost organ the carpel ; we cannot proceed any 

 further we can only go deeper into the interior of the 

 carpel, the cavity of the ovary. We shall find there 

 ovules, as has already been said. What are these ovules ? 



