186 Bulletin Wisconsin Natural History Society. [Vol. 8, No. 4. 



visiting those of L. cardinalis growing close by, as also the red 

 flowers of a hybrid of these two species of Lobelia. At Milwau- 

 kee, as also at Maiden Rock, Wis., I have on more than one 

 occasion noticed this visitor at the flowers. 



Giving all of these facts due consideration, there is hardly any 

 reason to doubt that red flowers receive more attention on the 

 part of the humming-bird than is the case with flowers otherwise 

 colored. Of the eleven flowers which were seen by the writer to 

 be visited at Milwaukee or at other points in Wisconsin, five are 

 red or reddish, three yellow, two green, and one purple. Blue is 

 not represented in any of them, and a glance at the list of flowers 

 visited by the ruby-throat (Knuth's Handbuch der Blueten- 

 biologie, Vol. Ill, part II, pp. 364-365) shows a remarkably small 

 percentage of blue flowers. The behavior of this bird in a locality 

 where red and blue Lobelias were growing together (Robertson) 

 and where preference was given to the red flowers is significant. 



In looking for an explanation in this matter my attention was 

 directed to the results obtained by C. Hess 9 in his studies on the 

 light sense and color sense in birds of diurnal habits (chickens 

 and pigeons). Hess has shown that these birds perceive the 

 colors on the red side of the spectrum (the side with long light 

 waves) to the same extent that we do, while on the side corre- 

 sponding to the short waves their perception of any part of the 

 spectrum beyond green is partly or entirely out of question. The 

 outside world with all its colors appears to them the same as it 

 does to the human eye when the latter sees the objects through 

 red or yellowish-red glasses. The meaning of this is, that such 

 birds are able to perceive red, yellow and green more or less dis- 

 tinctly, but green-blue, blue, and violet to a slight extent only, or 

 not at all. Viewed in the light of these facts the greater percentage 

 of visits to flowers, the colors of which correspond to the red side 

 of the spectrum, and the small percentage of visits to blue or 

 violet flowers is more easily explained. 



9) C Hess, Ueber Lichtsinn und Farbensinn der Tagvoegel; Archiv. 

 f. Augenheilkunde, Vol. 57, No. 4 (1907). 



Milwaukee Public Museum, 

 October 24, 1910. 



