192 MISCELLANEOUS OBJECTIONS TO THE 



in others the lower ones alone are fertilized ; and he sug- 

 gests that this probably depends on the direction in which 

 the pollen-tubes enter the ovarium. If so, the position of 

 the ovules, even when one is erect and the other suspended 

 within the same ovarium, would follow the selection of any 

 slight deviations in position which favored their fertiliza- 

 tion, and the production of seed. 



Several plants belonging to distinct orders habitually 

 produce flowers of two kinds — the one open, of the ordi- 

 nary structure, the other closed and imperfect. These two 

 kinds of flowers sometimes differ wonderfully in structure, 

 yet may be seen to graduate into each other on the same 

 plant. The ordinary and open flowers can be intercrossed ; 

 and the benefits which certainly are derived from this pro- 

 cess are thus secured. The closed and imperfect flowers 

 are, however, manifestly of high importance, as they yield 

 with the utmost safety a large stock of seed, with the ex- 

 penditure of wonderfully little pollen. The two kinds of ' 

 flowers often differ much, as just stated, in structure. The 

 petals in the imperfect flowers almost always consist of 

 mere rudiments, and the pollen-grains are reduced in 

 diameter. In Ononis columnse five of the alternate sta- 

 mens are rudimentary ; and in some species of Viola three 

 stamens are in this state, two retaining their proper func- 

 tion, but being of very small size. In six out of thirty of 

 the closed flowers in an Indian violet (name unknown, 

 for the plants have never produced with me perfect flow r ers), 

 the sepals are reduced from the normal number of five to 

 three. In one section of the Malpighiaceae the closed 

 flowers, according to A. de Jussieu, are still further modi- 

 fied, for the five stamens which stand opposite to the sepals 

 are all aborted, a sixth stamen standing opposite to a petal 

 being alone developed ; and this stamen is not present in 

 the ordinary flowers of this species; the style is aborted; 

 and the ovaria are reduced from three to two. Now al- 

 though natural selection may well have had the power to 

 prevent some of the flowers from expanding, and to reduce 

 the amount of pollen, when rendered by the closure of the 

 flowers superfluous, yet hardly any of the above special 

 modifications can have been thus determined, but must 

 have followed from the laws of growth, including the func- 

 tional inactivity of parts, during the progress of the reduc- 

 tion of the pollen and the closure of the flowers. 



It is go necessary to appreciate the important effects of 



