PREFACE TO THE SECOND EDITION. 



Since the publication of the first edition of this book 

 in 1877, several articles have appeared on the subjects 

 therein discussed, and many letters have been receiyed 

 by me. I will here briefly state their nature, as an 

 aid to any one who may afterwards pursue the same 

 subjects. The text has been left as it originally 

 appeared, excepting that a few errors have been 

 corrected. 



Dr. A, Ernst has proved in the clearest manner 

 {Nature, Jan. 1, 1880, p. 217), that MelocMa parvifolia, 

 which is a common plant near Caracas, is heterostyled. 

 The poUen-grains differ in the usual manner in size in 

 the two forms, as do the papillae on their stigmas. 

 The illegitimate unions, especially when pollen from 

 the same flower was employed, were much less fertile 

 than the legitimate ones, A new family, the Bytt- 

 neriacese, is thus added,tQ those including heterostyled 

 plants. 



Errara and Gevaert have published a paper on the 

 heterostylism of Primula, elatior in Bull. Soc. R. Bot. 

 Belg., tom. xvii. 1879. 



I have quoted (p. 100) Dr. Alefeld's statement that 

 none of the American species of Linum are heterostyled. 

 This statement was disputed by Kuhn (Bot. Zeit. 1866, 

 p. 1201), but has since been confirmed by Dr. Ign. 



