368 Cooke and Schively on Observations on the 



corolla is long and tubular, with open mouth. The style is 

 very much longer here, each stamen is much better devel- 

 oped, as is also the nectary. Otherwise, the flowers are 

 similar. The intermediate flowers have short tubular open 

 corollas. The lengths of style and stamens are about midway 

 between those of the cleistogamic and chasmogamic struc- 

 tures. 



So these chasmogamic flowers are to be regarded as more 

 primitive structures, persisting before the degrading influ- 

 ence of parasitism had affected the plant. The intermediate 

 flowers show the course taken by increasing degeneration, in 

 so modifying the flower as to produce the present function- 

 ing cleistogamic blooms. 



Histology of the Mature Stem. 



The aerial stem is triangular or tri-lobed in section, the 

 lobes being separated by three deep grooves. These grooves 

 are quite densely filled by hair outgrowths, though hairs are 

 rare on the outer lobed portions of the stem. They are 

 purely epidermal outgrowths, and vary much in size and in 

 the number of constituting cells. Some are of eight cells, 

 lying in a single row, and capped at the outer end by a trans- 

 verse row of two or four cells. These multicellular hairs 

 are the densest of all, containing rich cytoplasm and gran- 

 ular cell contents. Other hairs are long single cells, as large 

 as the entire multicellular. These are empty and vacuolated, 

 with a little faintly staining cytoplasm about the wall. It 

 seems likely that these are worn-out multicellular hairs in 

 which the cross walls have all or partly broken down. Some 

 hairs show clear cuticular caps along their outer cell walls. 

 These hairs are nearly all thin-walled, with a swollen turgid 

 aspect, well adapted for an absorbing function. They must 

 hold back and collect the water trickling down the grooves 

 in the stem, and may even take up this water and its dis- 

 solved salts. 



