ON THE ASCLEPIAUE^. 199 



constant than the manner in which the pollen is attached 

 to the processes of the stigma in each species ; and as con- 

 siderable differences in this respect take place in various 

 species, I have with advantage employed these in the new 

 generic divisions of the order which I have attempted to 

 establish, and to which I now proceed. 



As I have everywhere mentioned the sources from which 

 my knowledge both of genera and species is derived, it 

 becomes unnecessary particularly to notice here the extent 

 of my obligations to the unrivalled Herbarium of Sir 

 Joseph Banks, who, with his accustomed liberality, has 

 permitted me to examine, and, where necessary, to dissect 

 such specimens as seemed to. have any peculiarity of struc- 

 ture, and has thus enabled me to found my genera on a 

 more satisfactory induction than I could have done in any 

 other part of the world. 



