2 INTRODUCTION. 



the individuals of whicli exist under two or three 

 forms, differing in the length of their pistils and 

 stamens and in other respects, jj^hey were called hy 

 me dimorphic and trimorphic, but have since beeH 

 better named by Hildebrand, heterostyled.* As I 

 have many still unpublished observations with respect 

 to these plants, it has seemed to me advisable to re- 

 publish my former papers in a connected and cor- 

 rected form, together with the new matter. It will he 

 shown that these heterostyled plants are adapted for 

 reciprocal fertilisation ; so that the two or three forms, 

 though all are hermaphrodites, are related to one 

 another almost like the males and females of ordinary 

 unisexual animals. I will also give a full abstract of 

 such observations as have been published since the 

 appearance of my papers ; but only those cases will be 

 noticed, with respect to which the evidence seems fairly 

 satisfactory. Some plants have been supposed to be 

 heterostyled merely from their pistils and stamens 

 varying greatly in length, and I have been myself 

 more than once thus deceived. With some species the 



of the Proceedings of the Linnean P. elatior, Jaoq. ; and on the 



Society,' vol. vi. 1862, p. 77. Hybrid Nature of the Common 



" On the Existence of Two Oxlip. With Supplementary Ee- 



Forms, and on their Eeciprocal majkB on Naturally Produced Hy- 



Sexual Relation, in several Species brids in the Genus Verbiscum." 



of the Genus Linum." Ibid. vol. Ibid. vol. x. 1868, p. 437. 



vii. 1863, p. 69. • The term "heterostyled" does 



" On the Sexual Relations of the not express all the differences be- 



ThreeFoimsolLyfhrvmsalicaria." tween the forms ; but this is a 



Ibid. vol. viii. 1864, p. 169. failure common in many oases. 



" On the Character and Hybrid- As the term has been adopted by 



like Nature of the Offspring from writers in various countries, I am 



the Illegitimate Unions of Dimor- unwilling to change it for that of 



phio and Trimorphic Plants." heterogone or heterogonous, though 



Ibid. vol. X. 1868, p. 393. this has been proposed by so high 



" On the Specific Differences an authority as Prof. Asa Gray : 



between Primula veris, Brit. Fl. see the 'American Naturalist," 



(var. offioinalis, Ijmn.),P.vulgant, Jan. 1877, p. 42. 

 Brit. Fl. (var. aoaulit, Linn.), and 



