6 ELEMENTS OF BOTANY. 
Notice the presence of a distinct plumule, consisting of a pair of 
rudimentary leaves between the cotyledons, just where they are joined 
to the top of the caulicle. 
Make a sketch of these leaves as they lie in place on one of the 
cotyledons, after the bean has been split open. 
Note the cavity in each cotyledon caused by the pressure of the plumule. 
Place that cotyledon from which the sketch was made on the stage of the 
compound microscope under the lowest-power objective which the micro- 
scope has (say 2-inch), with light thrown on the object from above, and 
sketch the plumule as thus shown.! 
‘4, Examination of the Pea. —There are no very important points of 
difference between the bean and pea, so far as the structure of the seed is 
concerned, but the student should rapidly dissect a few soaked peas to get 
an idea of the appearance of the parts, since he is to study the germina- 
tion of peas in some detail. 
Make only one sketch, that of the caulicle as seen in position after the 
removal of the seed-coats.? 
~5. Germination of the Bean and the Pea. —Soak some beans as directed 
in § 3, plant them, and sketch as there directed. 
Follow the same directions with some peas.? 
6. Germination of the Horse-Chestnut.— Plant some seeds of the horse- 
chestnut or the buckeye, study their mode of germination and make out 
the nature and peculiar modifications of the parts. 
Consult Gray’s Botanical Text-Book, vol. I, pp. 19, 20. 
'%. Conditions Requisite for Germination. — When we try to 
enumerate the external conditions which can affect germina- 
tion, we find that the principal ones are light, heat, moisture, 
and presence of air. A few simple experiments will show 
what influence these conditions exert. 
‘8. Experiment 14 (a) Does Light assist Germination? (b) Does 
Light retard Germination ? — Put a piece of blotting-paper in the bottom 
*1The teacher should at this point give a short illustrated talk to explain in a 
general way the construction and use of the compound microscope. See Appendix A. 
* 2The teacher will find excellent sketches of most of the germinating seeds 
described in the present chapter in Miss Newell’s Outlines of Lessons in Botany, 
Part I, and in Gray’s Lessons in Botany. 
' 3 The pupil may economize space by planting the new seeds in boxes from which 
part of the earlier-planted seeds have been dug up for use in sketching, ete. 
. # This may readily be made a home experiment. : 
