FERTILIZATION. 177 
in various stages of maturity, he may investigate its adaptations for 
insect fertilization and its mode of protecting its pollen from creeping 
insects and from rain. It will be particularly interesting to compare the 
various degrees of perfection with which closely related flowers attain 
these results. Several flowers should be worked out pretty fully and the 
results of the examination of each recorded in a written account and a 
series of sketches. Out of the many possible studies of this kind the 
following are suggested : 
The flower of the pea, the bean, or the locust, consulting Figs. 159, 
160, 161. 
Fia. 160.— I, Diagram of Flower of Sweet Pea. II, Vertical Section of Flower 
(magnified). III, Calyx (magnified). 
