1885.] 
{ F lowers and F ruits. 
547 
mentioned the early or late time of flying ( Osmia tufa , An- 
thophora pihpes) ; an increased demand for nourishment 
(Apis Bomous) ; great demand for pollen ( Heriades truncorum 
Frosopis) ; peculiarities of the structure of the nest (Anthi- 
duini mamcatum, which has a short trunk, lines its nest with 
the woolly hairs of leaves, and consequently prefers the 
nairy Labiatae to the Papilionaceas, though it could obtain 
noney much more conveniently from the latter). 
Muller recognised to some extent the influence of such 
taciors, yet he laid far too little weight upon them, though 
their importance can be shown from his own statistical 
lesults. . It appears therefore inadmissible to found the 
progressive development of flowers and insets solely upon 
the elongation of the trunk. In this respecft Muller’s theory 
is in need of modification. J 
