260 Principles of Plant Culture. 
bean plant, with simple lenses of rather high magnifying 
power. lf a compound microscope is available, many 
mounted objects illustrating the cell structure of plants are 
also shown. 
Absorption of water by seeds (26). Hach student is pro- 
vided with a graduated glass cylinder of at least 50 cubic 
centimetres capacity, (one to each pair of students will an- 
swer), and two bottles of at least 100 c.c. capacity, with 
corks. Each bottle should have a strip of white paper 
pasted vertically upon it to receive the name of the student 
and other data. 
Each student measures the volume of 50 fresh seeds of 
the bean, pea, or Indian corn, by dropping them into, the 
graduated cylinder that has first received 25 c. c. of water. 
The height to which the water rises after receiving the seeds 
ig then quickly and accurately noted, when the volume of 
the seeds is determined by substracting 25 c. c. from this 
reading. The student then pours the seeds, with the water, 
into one of his bottles, corks the latter and writes his name, 
with the date, on the paper pasted on its side. He then re- 
peats the process with seeds of the honey locust, yellow 
wood or some other seed that does not readily absorb cool 
water, and after recording the data in his notebook, places 
the bottles in a warm place until the following day, when 
he again measures the volume of the two kinds of seed. 
The seeds placed in the first bottle will usually be found to 
have nearly or quite doubled in size while those in the sec- 
ond bottle have scarcely swollen at all, 
Next, show the class a sample of the second lot of seeds 
that have fully swollen from soaking in hot water. Impress 
upon their minds the fact that while most seeds readily absorb 
moisture at ordinary temperatures, a few kinds do not, and 
seeds of the latter class need to be soaked cautiously before 
planting, in hot water, until they swell (27d). 
The rate at which seeds absorb water depends 
a— Upon the water content of the medium (27).* Determine 
the volume of 3 samples of navy beans. Place one sample 
in water, a second in very damp earth and the third in 
*In the three exercises under this head, the volume of the seeds needs to be 
determined the first time without wetting them, hence very fine clean sand is used 
instead of water in the graduated cylinders. ‘The sand should be carefully shaken 
down between the seeds in every case. While the sand is sowewhat Jess accurate 
than water, the principles stated may be readily demonstrated by this means. 
