142 
MANUAL OF NATURK STUDY. 
each grain of which is just as definite in form as a 
grain of corn is definite, or a mustard seed is defin¬ 
ite in form. As the form of seeds varies in differ¬ 
ent plants, just so does the form of pollen vary in 
different plants. So certainly is this true that 
the plants may sometimes be determined by the 
shape of the pollen alone. 
For examples of these different forms, see the 
lily with its smooth, oval pollen grains; the sun¬ 
flower with its spherical pollen grains, beset with 
prickly projections; the musk plant pollen with its 
spiral grooves, the evening primrose with its three 
lobes as large as the central body, and so on, the 
pollen grains of each kind of plant differing in 
form from those of all others. But these forms 
cannot be seen without the aid of a good micro¬ 
scope. The other parts of the flower can be seen 
very well with a good hand lens. Every pupil 
ought to have such a lens in order to get best re¬ 
sults from an examination of these delicate parts 
of the plant. 
Note the opening of the anther. Does it open on 
the inside next the pistil, or on the outside away 
from the pistil? 
Now examine the pistil. Review the parts of 
pistil as in third grade work and note the relation 
of stigma and pollen to each other and to the 
ovules within the ovary. <• 
