POLLINATION AND FERTILIZATION. 20/ 



ovule with reference to its stalk. The funicle is the stalk of the 

 ovule, the hilum is the point of attachment of the ovule with 

 the ovary, the raphe is the part of the funicle in contact with 

 the ovule in inverted ovules, the chalaza is the portion of the 

 ovule where the nucellus and the integuments merge at the base 

 of the ovule, and the micropyle is the opening at the apex of 

 the ovule where the coats do not meet. 



340. In the pines and other gymnosperms the male and 

 female prothallium, as regards structure and development, are 

 intermediate between those of the higher plants and the ferns, 

 but they are nevertheless much reduced. For a full discussion 

 of the prothallium and sexual organs of the gymnosperms and 

 angiosperms see the author's larger "Elementary Botany," 

 Chapters XXXI, XXXII, and XXXIV, and for pollination, see 

 Chapter L. 



Material. — To show the male and female prothallium of angiosperms. 

 Pollen grains of several species may be germinated in a weak solution of 

 sugar in water, and these studied with the aid of the microscope, to see the 

 pollen tube. 



The female prothallium (embryo sac in different stages) can be obtained 

 by making sections of ovules just before and after fertilization. The lily 

 is a good one to use, since there are many ovules standing at right angles 

 to the pistil. Cross-sections of the pistil afford many good sections of the 

 ovules where they are carefully made. Permanent slides can be purchased 

 of supply companies. 



