28 FOUNDATIONS OF BOTANY 
of structure between the two. Their mode of growth is 
also different, as the pupil may infer after he has tried 
Exp. XIV. 
37. Discrimination by Staining. — For some reason, per- 
haps because the skin or epidermis of the young root is 
not so water-proof as that of the stem, the former stains 
more easily than the latter does. 
*EXPERIMENT XIII 
The Permanganate Test. — Make a solution of potassium perman- 
ganate in water, by adding about four parts, by weight, of the crystal- 
lized permanganate to 100 parts of water. Drop into the solution 
seedlings, e.g., of all the kinds that have been so far studied, each in 
its earliest stage of germination (that is, when the root or hypocotyl 
has pushed out of the seed half an inch or less), and also at one or 
two subsequent stages. After the seedlings have been in the solu- 
tion from three to five minutes, or as soon as the roots are consider- 
ably stained, pour off (and save) the solution and rinse the plants 
with plenty of clear water. Sketch one specimen of each kind, col- 
oring the brown-stained part, which is root, in some way so as to 
distinguish it from the unstained hypocotyl. Note particularly how 
much difference there is in the amount of lengthening in the several 
kinds of hypocotyl examined. Decide whether the peg of the squash 
seedling is an outgrowth of hypocotyl or of root. 
' 38. Disposition made of the Cotyledons. — As soon as 
the young plants of squash, bean, and pea have reached 
a height of three or four inches above the ground it is 
easy to recognize important differences in the way in 
which they set out in life. 
The cotyledons of the squash increase greatly in sur- 
face, acquire a green color and a generally leaf-like appear- 
ance, and, in fact, do the work of ordinary leaves. In 
