REPRODUCTION 53 
by insects. The insect finds food in the form of nectar and 
sometimes pollen, and as it is obtaining this food it may be 
forced to move about in such ways that proper placing of 
the pollen will result. To be most successful the floral or- 
gans must be so arranged that close-pollination will be pre- 
vented and cross-pollination secured. The adaptations for 
effecting these things are extremely varied, and are some- 
times quite intricate, though they are by no means always 
completely successful. 
In each flower studied notice: 
Form.—Whether open, petals or sepals united into a 
tube, stamens and carpels enclosed, and whether stamens 
and carpels are of the same length in all flowers. 
Color.—Are the floral leaves bright or somber in color? 
Odor.—What function do you think the color and odor 
may serve. 
Nectar.—If present, in what part of the flower is it 
developed? Does it vary in amount in different flowers? 
Is it equally abundant in old and young flowers? Is it 
placed where insects get to it easily? Note whether the 
insect, in obtaining nectar, probably passes the anthers and 
stigma, and if so, whether it probably passes one before the 
other. From the structure of the flower do you think the 
same part of the insect’s body would strike both anthers 
and stigmas? From the structures do you think the flower 
prevents close- and obtains cross-pollination? If possible 
to study flowers while insects are working upon them, ob- 
serve closely to see just how entrance to the flower is made, 
and what parts of the insect’s body come in contact with 
anthers and stigma, and the order in which contact is made. 
Determine whether the plant is successful in cross-pollina- 
tion. Catch one of the insects and examine under low 
power of the microscope to see what parts of his body, if 
any, have pollen-grains upon them. 
Does an insect, when leaving a flower, usually retrace 
