ELEMENTS OF STKUCTUKAL BOTANY. 13 



17. Ill orilei- that ovules may become seeds, it is 

 always essential that they should be fertilized in the 

 manner just described. If we prevent pollen from 

 reaching the stigma — by destroying the stamens, for 

 instance— the ovules simply shrivel up and come to 

 nothing. 



Now it is the business of the flower to produce seed, 

 and we have seen that the production of seed depends 

 mainly upon the stamens and the pistil. These organs 

 may consequently be called the essfiitial o)y<t)is of he 

 flower. As the calyx and corolla do not play any direct 

 part in the production of seed, but only protect the 

 essential organs, and perhaps attract insects, we can 

 understand how it is that they, as a rule, disappear 

 early. Their work is done when fertilization has been 

 accomplished. 



Having noticed thus briefly rne part played by each 

 set of floral organs, we shall now proceed to the exami- 

 nation of two other plants, with a view to comparing 

 their structure with that of the Buttercup. 



CHAPTER III. 



EXAMINATION OF HEPATICA AND MARSH-MARIGOLD — RESEM- 

 BLANCES BETWEEN THEIR FLOWERS AND THAT OF 

 BUTTERCUP. 



18. Hepatica. You may procui-e specimens of the 

 Hepatica almost anywhere in rich dry woods, but you 

 will not find it in flower except in spring and early 

 summer. Lt is very desirable that you should have the 

 plant itself, but for those who are unable to obtain 



