18 



He showed tliat flowers ware composed of two classes of 

 organs, the outer ones, consisting of the sepals and the petals, 

 having chiefly protective functions to perform ; whilst the inner 

 ones, consisting of the stamens and carpels, were designed for the 

 reproduction of the plant. 



The decorative value of any plant depended as a rule upon 

 the form and colour of the protective organs, more particularly 

 the petals as the sepals forming the outside row of organs were as 

 a rule green and inconspicuous. 



Taking the diagram of the Liliaceoe (Lily tribe) in the first 

 place and comparing it with that of the Ranunculaceae (Buttercup ■ 

 tribe), he explained how it was that the plants of the former type 

 were generally so much less double than those of the latter 

 having so stamens as compared with the latter. 



There were two ways in which the extra petals which 

 constituted the double flower were derived; in the first place by a 

 kind of doubling of the existing petals, and in the second by the 

 conversion of stamens into petals. In some cases only the latter 

 mode was concerned in the formation of the extra petals, but in 

 the more double ones, both of the modes operated in producing 

 the final product. When the extra petals were produced by the 

 doubling of the whorls of petals the resulting products were in no 

 way distinguishable from the original petals, but on the other hand 

 petals which had been evolved from stamens, nearly always showed 

 more or less evident traces of their origin in the form of parts 

 of the anther growing on the edge or in the centre of such petal. 

 These portions of anther might or might not contain any pollen 

 grains. 



On dissection of any of our double flowers it was easy to 

 pick out examples showing the gradual transition from perfect 

 stamen to more or less perfect petal, and the lecturer then pro- 

 ceeded to show a complete series of such forms taken from such 

 familiar old friends as Geraniums, Primulas, Azalias, and 

 Daffodils, with many others. These forms were described and 

 passed round whilst the subject was further illustrated by black- 

 board sketches of a series of the extra petals from Azalia with a 

 normal stamen showing the various steps generally to be found 

 in double flowers. 



In many of these part only of the stamen was concerned in 

 the change, that part being the filament, whilst in the extreme 

 cases their position only afforded evidence as to their origin. 



