LAW OF PROG RE SSI VE COL O URA TION. 37 



lated with the visits of insects, for the two highly 

 abnormal petals under the helmet of the monkshood 

 produce honey, as do also the two long petals within the 

 spur of the larkspur. Both flowers are also specially 

 adapted to the very highest class of insect visitors. 



Fig. 12. — Flowers of monkshood {Aconitum «rt/^//«i), dark blue. 



Aconitiim is chiefly fertilized by bees ; and Sir John 

 Lubbock observes that '^ Anthophora pilipes and Born- 

 bus hortorum are the only two North European 

 insects which have a proboscis long enough to reach 

 to the end of the spur of Delphiniiun elatum. A, 



