7i6 
CHEMICAL PROCESSES IN THE PLANT. 
endosperm which is then completely emptied and reduced to a thin membranous sac. 
They now rise above the ground, become expanded to the light where they continue 
to grow rapidly and become green, and serve from this period as the first assimilating 
organs. 
In this case, as in the germination of all oily seeds, sugar and starch are produced 
here in the parenchyma of every growing part, disappearing from them only when the 
growth of the masses of tissue concerned has been completed. Since the endosperm 
grows also independently, starch and sugar are, in accordance with the general rule, 
temporarily produced in it. The cotyledons apparently absorb the oil as such out of 
the endosperm, whence it is distributed into the parenchyma of the hypocotyledonary 
portion of the stem and of the root, serving in the growing tissues as material for the 
formation of starch and sugar, which on their part are only precursors in the pro- 
duction of cellulose. In these processes of growth tannin is also formed which is of 
no further use, but remains in isolated cells, where it collects apparently unchanged 
Fig. ^■ji.— Ricinus communis; I longitudinal section of the ripe seed; // germinating seed with the cotyledons still 
in the endosperm (shown more distinctly in A and B), s testa, e endosperm, c cotyledon, he hypocotyledonary portion 
of the stem, iv primary root, w' secondary roots, x the caruncle. 
until germination is completed. It can scarcely be doubted that the material for the 
formation of this tannin is also derived from the oil of the endosperm, although perhaps 
only after a series of metamorphoses. The absorption of oxygen, which is an essential 
accompaniment of every process of growth and especially of germination, has in this 
case, as in that of all oily seeds, an additional significance, inasmuch as the formation of 
carbo-hydrates at the expense of the oil involves the appropriation of oxygen. 
Since the metamorphoses of material proceed pari passu with the growth of the 
separate parts, the distribution of the products of metastasis through the tissues is 
continually changing, and can only be understood by a consideration of all the sur- 
rounding circumstances. The micro-chemical investigation of seedlings in the state 
represented in Fig. 471 77, gives, for instance, the following result: — in the endo- 
sperm is found a great deal of oil and a little starch, with sugar at the outside ; the 
epidermis and parenchyma of the slowly growing cotyledons are filled with drops of 
oil ; a large number of the epidermal cells contain tannin ; starch-granules are found 
