ILLUSTRATIONS. 



PLATES. 



Page. 

 Plate I. Fig. 1. — Growing tobacco blossoms at time of emasculation. Fig. 2. — 



Same blossoms as in fig. 1, two days later 42 



II. Fig. 1. — Same blossoms as in PI. I, fig. 1, eight days later. Figs. 2, 3, 



4, 5. — Photomicrographs of tobacco pollen tubes 44 



III. Tobacco blossoms and seed pods 46 



IV. Methods of emasculation; also a grape cluster showing difference in 



size between seedless and seeded berries 48 



TEXT FIGURE. 



Fig. 1. Flowers of Sabbatia angularis: (a) Appearance while pollen is being 

 shed; (6) Stigma and anthers avoiding each other; (c) Receptive 

 stigma and deciduous anthers 37 



8 



