SUBJECTIVE LESSONS.* 
Factors of Evolution (Chapter II, pages 14-16).—Give 
examples illustrating the diversity shown in the structure 
and habits of birds. What theory has been advanced to 
account for the wide variation in structure shown by birds ? 
What is meant by Natural Selection? How does the 
theory of Lamarck differ from that of Darwin? How 
may the tail-feathers of the Woodpecker have acquired 
their present pointed shape? Is it probable that the Wood- 
pecker’s barbed tongue has been acquired in the same 
manner ? 
Form Aanp Hasir. 
The Wing (Chapter II, pages 17-24).—Name the fune- 
tions of the wing. What is doubtless its most primitive 
use as an organ of locomotion ? How is it used by young 
Gallinules? By the young Hoatzin? How is it used by 
Grebes and Penguins? By the Ostrich ? What variation 
in expanse of wings is presented by birds? What rela- 
tion exists between shape of wing and style of fliglit? 
Give illustrations. Mention some flightless birds. Why 
is flight necessary to the Razor-billed Auk? Under what 
conditions might it exist without the power of flight? 
What group of flightless birds is found in the Antarctic 
region ? Where do they nest? Why? What birds be- 
come temporarily flightless? In what manner? What 
lake is inhabited by a flightless Grebe? Where are flight- 
less Gallinules found ? How did they probably reach the 
islands they now inhabit? Mention other flightless birds. 
* The value of these lessons will be greatly enhanced if the 
teacher will constantly have the pupil name additional species in 
illustration of the facts and theories here mentioned. 
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