DEGENERACY OF FLOWERS. 257 



of pollen-grains fall spontaneously oat of the anther-cone 

 into the stigmatic cavity and there develop long pollen- 

 tubes, even before the opening of the flower, in much rarer 

 cases a short time after it has opened. 



" When the visits of insects are prevented by a fine net, 

 the flowers of the small-flowered form wither two or three 

 days after opening, every one setting a vigorous seed- 

 capsule ; those of the large-flowered form remain in full 

 freshness more than two or three weeks, at length withering 

 without having set any capsule ; when fertilised they, too, 

 wither also after two or three days." 



I have met with several variations in minor details of 

 structure in the smaller-flowered kind. Thus in some the 

 stigmatic lip, probably representing one of the three stigmas, 

 formed a globular knob 

 protruding from the j Q^a 

 orifice, as shown in Fig. ^-' "^ 

 55, a, h. In another, 

 it protruded like a 



tongue, C. The lateral Fig. 55.— styles and stigmas of self-fertilising forms 

 T . 1 1 of Pansy. (For description, see text.) 



frmges,* which help to 



keejD the pollen back from reaching the stigmatic chamber in 

 the larger flowers, are more or less retained in these ; as is 

 also the bent-base to the style which forms the spring,* 

 which keeps the globular head in a downward position. 



The accompanying figures will illustrate the cleistogamous 

 flower-buds of Violets. They are very minute, about one- 

 eighth of an inch in length (Fig. 56, /). The petals are 

 reduced to linear and pointed structures, green or purplish 

 green, (a) ; or they may be altogether wanting. The spur 

 alone of the larger petal is sometimes present in strong- 



* For the theoretical origin of "fringes" and " springs," see Chap. 

 XV., p. 133, and Chap. XIII., p. 123, respectively. 



