20 THE LIFE OF THE PLANT 



fore reach the conclusion that the transformation of 

 one kind of leaf into another can be demonstrated not 

 only by observation, but also by means of experiment, 

 generally by far the more convincing method. 



Proceeding with our study we reach the very heart of 

 the flower. After the stamens we meet the last organ of 



a flower — I say 

 the last because 

 it forms its ceh- 

 tral part and 

 thus terminates 

 its growth and 

 consequently the 

 growth of the 

 part of the stem 

 Fig. io. '^hi'^h ends in 



the flower itself. 

 This organ is called the carpel or pistil on account 

 of its form, which, with its swelled base (ovary), 

 elongated neck (style) , and rounded top (stigma) is very 

 like a pestle. 



There may be one or many carpels in a flower. The 

 lowest part of a carpel, the ovary, is hollow inside, so 

 that the whole organ in this illustration (fig. lo, flower 

 of cherry) is like a small bottle. This cavity contains 

 one, several, or even many bodies, round and white, 

 called ovules. We meet this organ again with distrust. 

 This time there seems to be not a trace of likeness 

 to a leaf, but another successful choice of illustration 

 will prove that this organ also is derived from one or 

 many little leaves. Some abnormal flowers will give us 

 the necessary clue. For instance in the double flowers 

 of the cherry the carpel often transforms itself from a 

 bottle-shaped organ into tiny leaves, one or two in 

 number (fig. 1 1).^ In many cases it is even unnecessary 



> A — Pistil partly transformed into a leaf. B — The same pistil in a. 

 transverse section. C — Pistil transformed into two leaves. 



