1914] East and Glaser—Relation Between Flower Color and Insects Pal 
segment, and the posterodorsal portion of the head is much less deeply and exten- 
sively infuscated. 
Described from four specimens taken by Mr. T. Fukai in the 
Saitama division of Japan. 
OBSERVATIONS ON THE RELATION BETWEEN FLOWER 
COLOR AND INSECTS. 
By E. M. East and R. W. GuaseEr. 
Bussey Institution, Harvard University. 
In 1909 a cross was made between the small red flowered Nico- 
tiana forgetiana Hort (Sand) and Nicotiana alata Lk. and Otto var. 
grandiflora Comes, the large white N. affinis of horticulture, for 
the purpose of studying certain problems of heredity. About 
fourteen thousand plants of the second, third and fourth hybrid gen- 
eration have been grown, and it has been established beyond a rea- 
sonable doubt that each plant is completely self-sterile though it 
crosses easily with any of its neighbors. Several hundred carefully 
controlled self-pollinations have not yielded a single seed, while 
histological studies have shown self-fertilization to be practically 
impossible. On the other hand, hundreds of artificial cross pollina- 
tions have yielded capsules full of seed in almost every instance, 
showing with what ease cross-fertilization takes place, for artificial 
pollination is usually not as successful as natural pollination. 
The fact that every capsule formed naturally on these plants must 
have resulted from a cross-pollination produced by an insect, 
serves to excuse our adding to the already huge literature on the 
relations between insects and plants. The sixteen different color 
forms that have segregated from the original cross permit observa- 
tions on the percentage of flowers cross-fertilized and the selective 
value, if any, of distinct color varieties. 
Our knowledge of the behavior of insects relative to flowers has 
been greatly extended during the past few years by the work of 
Plateau, Forel, Lovell, Greenicher and others, but it has resulted in 
that obscurity which precedes aggregation and precipitation by 
disclosing the marvelous complexity of the relation. The adjust- 
ment between certain insect forms and certain types of flowers is 
