EXPERIMENTS 13 
by thrusting pins thru the cotyledons. ‘The radicles 
must be parallel with the flat surface of the cork and 
must point toward its center. Arrange the clinostat so 
that the surface to which the peas are fastened 1s ver- 
tical. Moisten the blotting paper and cover the peas 
with the glass dish. Fasten the remaining three peas 
to a piece of wood, previously soaked in water, so that 
the radicles point in different directions, and place them 
in a damp chamber in such a position that the surface on 
which the peas are found is vertical. Wind the clinostat 
every day and keep it running a week. The rotation 
neutralizes the effect of gravitation. Explain how this 
is done. Results; conclusions? 
Exp. 13, Class: Pour mercury into a tumbler to a 
depth of about 2 cm., then add water about 3 mm. deep. 
Fasten two peas with straight radicles about 1.5 cm. long 
to a piece of water-soaked wood tightly wedged in the 
tumbler in such a position that the radicles form an angle 
of about 30 degrees with the surface of the mercury and 
their tips extend to within about 2 mm. of it. 
Do the radicles grow into the mercury? Conclusion? 
Exp. 14, Class: In a wire basket nearly filled with 
wet sawdust plant a dozen peas and as many kernels of 
corn, so that they will lie about 1.5 cm. from the bottoin. 
Now set.the basket in a mioderately damp place in such 
a way that the bottom will make an angle of about 45 
degrees with the horizontal. 
Study the effect of moisture on the direction of 
growth of the radicles after they extend thru the bottom 
of the basket. Results: conclusions? 
Exp. 15, Groups of Two: As soon as the plants in 
