METAMORPHOSIS. 



143 



to the fusion of tlie anterior stamen of the outer whorl 

 (A-l) with the petal, for this stamen is absent from the 

 column. In a flower of Oypripedium insigne the two 

 lateral stamens of the inner whorl (a Y and a 2 ) were 

 absent, and the lateral petals were transformed into 

 labella (PI. XL, fig. 5). In these we see, apparently, 

 the labelliform character of the petal resulting from 

 the fusion with it of a stamen. Yet it is doubtful if 

 there is any real evidence in favour of the view that 

 the labelliform character is due to the incorporation 

 of stamens with a petal. 



Dendrobium nobile var. Goolcsonianum produces 

 flowers in which the lateral petals are transformed 

 into labella, or at any rate resemble them in most 

 particulars. In a " spike " of another variety of this 

 species all the flowers of one side were normal, while 

 those of the other side had labelliform petals ; in one 

 of the flowers one of the petals retained its normal 

 form and colour. In both varieties of Dendrobium 

 the " column " was perfectly normal ; hence there can 

 be no possible question of anthers fusing with the 

 petals to form the labella Examples of this kind tend 

 clearly to show that labellum-formation is an ordinary 

 form of heteropetalody, comparable to the change of 

 one perianth-leaf into another, either of the outer or 

 inner whorl. 



Theory of the Labellum. — The points brought for- 

 ward in favour of the Brownian and Darwinian hypo- 

 thesis for the origin of the labellum, viz., by the 

 incorporation of stamens with an ordinary petal, are 

 the following : 



1. The vascular cords which correspond to the two 

 stamens A 2 and A 3 pass, in many orchids, into the 

 lateral regions of the labellum. This, however, is of 

 no final value, for in other orchids the same cords are 

 seen to be attached to those supplying the column. 

 Moreover, the position of vascular strands cannot be 

 allowed to be a factor in solving morphological 

 problems. 



