FORMS OF FLOWERS. 195 



Species" was published in 1877, and a second edition 

 in 1880. This work, like so many others, had been 

 largely anticipated by the author's original papers 

 to scientific societies, in this case to the Linnean. 

 The papers were combined, brought up to date, and 

 with the addition of much new matter constituted 

 the volume. The chief part of the work is concerned 

 with heterostyled plants, viz. species which bear 

 different kinds of flowers chiefly distinguished by the 

 lengths of the pistil and stamens. As many as three 

 different forms occur in Ly thrum. In this work it is 

 shown that each of the forms, although possessing 

 both kinds of sexual organs, is adapted to be fertilised 

 by the pollen of another form, and that such offspring 

 are more vigorous than those produced by fertilisation 

 by the same form. He furthermore showed that 

 the offspring of " illegitimate " parentage (viz. those 

 which were fertilised by the same form) possessed, 

 in certain respects, a close resemblance to hybrids 

 among animals. He remarks in his Autobiography, 

 " No little discovery of mine ever gave me so much 

 pleasure as the making out the meaning of hetero- 

 styled flowers." 



In addition to the heterostyled flowers, the other 

 differing forms borne by the same plants are con- 

 sidered, including the cleistogamic species, in which 

 minute closed flowers are borne as well as the 

 ordinary open ones. The former are wanting in 

 the scents and colours of ordinary flowers, and 

 are specially adapted for self-fertilisation, and the 



