127 



July in which the enlyx remained closed over the dwarfed corolhi. The 

 only change in stnu-tnre noted was that the five shorter, stamens bore 

 aborted anthers, and that the pollen-bearing anthers were in contact with 

 the stigma. Contrary to what some writers state the stamens of 0. 

 Stricta are often dinorphic. Tlie self-poUenation of the normal flower is 

 accomplished by the corolla closing after exposnre. and pressing the 

 anthers against the stigma. 



One of the most interesting changes in structure from a conspicuous 

 to a cleistogamous flower is seen in the violet. The showy flowers are so 

 constructed that the honey-bee is the only insect that I know to be of 

 service in its fertilization, and only a part of the anthers are called into 

 tise by it. To reach the spur in which the nectar is stored, the bee, after 

 it settles, has to reverse iis position, and force its tongue l)etween the two 

 -appendages on the lower stamens. In doing this it comes in contact 

 -with the .stigma antl at the same time is dusted with pollen from the 

 appendagcd stamens. The an.tht rs of the other three stamens do not aid 

 in supplying the Itee with pollen, and seem to be of vei-y little if any use 

 to the plant. In the concealed fbnvcrs. they ai'c aborted. The pistil, of 

 the cleistogamous flowers of Mula Striiit>i Ait., is declined, so as to bring 

 the stigma against the end of the ovary, and in contact with the two con- 

 nivent anthers. Two appendages grow from the fertile stamens, just 

 below the anthers, that are expanded so as to cover the anthers and the 

 whole of the pistil. 



1. sti-i(it(i continues to iirodui-e showy flowers longer than many other 

 species, and as a consequence its concealed flowers come in summer. 



Viola pubescciis Ait. develops a few yellow flowers in early spring. It 

 continues to grow imtil August, and as it grows, concealed flowers are 

 developed in the axils of the leaves. 



The altruptness of the change from a showy to a cleistogamous flower 

 Avas beautifully shown on a plant of Impaticns hiffara that produced a w^ell- 

 •developed, consjiicuous flower on one branch of a peduncle and a concealed 

 flower en the other branch. 



The fact that the stigma of Tccoiun radicaiis returns to its former posi- 

 tion in two hours after it has l)een changed in response to an irritant, 

 unless the irritation has been accomplished by pollen of a certain quality, 

 shows that the process of fertilization begins within two hours after the 

 right kind of pollen has lieen applied, and that the stigma is endowed 

 with renuirkalde selective power. The whole process suggests the shad- 



