CHAPTER XIII. — THE FRUIT AND SEED. 



x °5 



5. Forcleistogamous flowers examine late in summer the runners concealed 

 underneath the leaves of Viola blanda, or of the English Violet (Viola odorata). 

 Examine carefully their structure, and observe in those which have fruited the 

 number of seeds produced. 



For the same purpose also study the cleistogamous flowers of Polygala 

 polygama, and compare them carefully with the showy flowers of the same 

 plant. 



As the study of the fertilization of the ovule is a matter of considerable 

 difficulty, and requires the use of high powers, it should be deferred until the 

 student has acquired the requisite skill in the use of the microscope. 



CHAPTER XIII. -THE FRUIT AND SEED. 

 I. — The Fruit. 



The fruit consists essentially of the ripened pistil or pistils, but 

 it may also include other organs which grow fast to it in the 

 process of their development. 



Its structure, in a general way, resembles that of the pistil or 

 gynaecium from which it is derived. The modifications which it 



Fig. 303. 



Fig. 304. 



Fig. 305. 



Fig. 303. — Ovary of Buckeye when in Flower, cut transversely, showing three loculi 

 and two ovules in each loculus. 



Fig. 304. — Ovary of Uuckeye, cut transversely at a later stage of development, show- 

 ing one ovule strongly developed, while the others have ceased their growth. 

 Fig. 305. — Capsule of Stramonium. 



undergoes in its development, in many cases at least, have refer- 

 ence to the dispersion of the seeds when they are ripened. 



The kinds of modifications that may take place are chiefly 

 the following : 



