48 THE AMERICAN NATURALIST. [Vor. XXXIV. 
and that the fragrance is either unperceived or is unpleasant 
to them. 
The tube of L. periclymenum is 22 to 25 mm. long, so that 
the honey, which may fill the tube for half its length, is also 
accessible to bumblebees. During the first evening the inte- 
rior of the flowers is white, and the matured anthers stand 
directly in front of the entrance, while the stigma is bent 
abruptly downward. On the second evening the color within 
has changed to yellow, the stigma has moved upward and 
stands in front of the flower, while the anthers are in turn 
bent downward. It is doubtless designed that moths should 
visit the flowers in the first stage before those in the second. 
Knuth was, however, unable to determine in the evening which 
kind of flowers was sought first, as the moths move with great 
rapidity. In this connection the color change is probably of 
not much significance. The hawk-moth flowers were once 
bumblebee flowers, with yellowish coloration. After the hawk 
moths had dispossessed the bees, the production of yellow pig- 
ment was no longer beneficial, and consequently tended to dis- 
appear. Its reappearance in the older flowers is due partly to 
reversion and partly to oxidation, for the flowers in wilting 
continue to darken and turn a dingy orange-brown. More- 
over, yellow is probably as conspicuous as white in the even- 
ing, and nocturnal flowers, as the evening primrose, CEzotLera 
biennis, may be yellow-colored. 
On the Island of Fóhr, Knuth collected: Sphingida, 5; 
Noctuidz, 1; Diptera, 4; Bombus, 1. The same observer 
saw in Helgoland: Sphingide, 2; Noctuidae, 2. Heinsius 
saw in Holland: Bombus, 1, as well as many pollen-eating flies. 
Macleod observed in Belgium: Bombus, 2; Sphingide, 1. 
5. Ornithophilous or Bird Flowers. — L. sempervirens L. is 
fertilized by the ruby-throated humming bird. The narrow tube 
is 25 to 35 mm. long, with a regularlimb. The color is scarlet 
outside, yellow within, or rarely throughout. The flower is 
scentless. Crimson or scarlet is the characteristic color of 
bird flowers, as Lobelia canadensis and Tecoma radicans. Red 
appears to be the favorite color in bird zsthetics, and a larger 
number of edible fruits display this hue than any other. Of 
