264 Principles of Plant Culture. 
Plant protectors (279). Require each student to make at 
least one plant protector, as shown in Fig. 56, patterns for 
which are to be furnished. 
Kerosene emulsion (294). Let each student make a given 
quantity of the kerosene emulsion after one of the formulas 
given. 
Spraying pumps (304). Give at least one exercise to the 
construction and use of spraying pumps and nozzles. 
Prevention of grain smuts (325). Require the students to 
treat a quantity of oats to hot water as described. 
Bordeaux mixture (329). Require each student to make 
a stated quantity of the Bordeaux mixture after the for- 
mula given. 
Propagation by seeds (344). Instruct the students in the 
use of the hand seed-drill and broadcast sower. Let them 
ascertain how much clover seed the broadcast machine is 
sowing per acre, by laying on the ground or floor several 
sheets of paper, exactly one foot square, painted with 
glycerine to catch the falling seeds. Having learned the 
average number of seeds deposited per square foot with a 
given rate of motion of the machine, let the students com- 
pute the number of seeds sown per acre, and reduce this to 
ounces. The number of clover seeds in an ounce may be 
ascertained by dividing an ounce of the seed among the 
students for counting. 
Propagation by layers (349). Instruct the students in lay- 
ering canes of the grape, and in mound-layering the stems 
of the gooseberry. 
The bulb (352). Dissect bulbs of the onion, tulip, lily etce., 
ascertaining their structure and finding the embryo 
flowers. 
The cold-frame (364). Require the students to make a 
drawing and write a description of a cold-frame, from a 
model furnished them. 
The hotbed (365). Let the students assist in making a 
hotbed after the plan described. Also let them note the 
temperature of the soil within the frame on several succes- 
sive days after the bed is finished, and give them instruction 
in ventilating the hotbed. 
The propagating bed (368). Require the students to make 
a propagating bed in the greenhouse, after the plan described. 
Stem cuttings (373-375). Let the students make cuttings 
