_ If this pea had been planted in the ground, there would 
have been formed under favourable circumstances, from the 
growth of the axis of the embryo, the s¢em directed upwards 
‘and the 7vof directed downwards. When theseed germinates 
(Fig. 99), a smaller or larger number of lateral organs, the 
; Seatrary sh skin. rok testal j is ae from a pea gh Shas” 
been soaked in water, two large fleshy masses are seen, hee : 
cotyledons, enclosing a small cylindrical body, the axzs (Figs. 
97, 98), which bears two minute leaves at its extremity; 
the cotyledons and axis together constituting the embryo. 
leaves (¢ d), develope, but only on the ascending portion of 
Le 
1 
I 
% 
iy 
( 
EC oo 
v : 
e FP 
Fic. 97.—Pea, with its testa cut Fic. 98.—Pea split open and with the 
through; c cotyledons; G the testa removed; F small cavity in 
plumule enveloped in minute which the plumule or apex of the 
leaves ; R radicle; T axis.of the stem lay ; the other letters as in Fig. 
embryo ; I outcr, E inner inte- 97 (somewhat magnified). 
gument ; F funiculus; P part of 
the pericarp (diagrammatic). 
the axis, not on the root. The form of the leaves is very 
various according to their function in the life of the plant; 
certain of them unite, in the form of floral leaves, together 
with the stem, to produce the flower. From a particular — 
part of the flower is developed the fru, within which are - 
produced the seeds destined for the reproduction of the — 
species. Epidermal structures (trichomes), inal clothe the a 
surface at different parts. 
If the history of development of an embryo, as that of 
the pea, is examined more closely, it is found that from a_ 
evomnly. plastic mass of similar cells the root is developed 
* 
