Fig. 91.
Fig. 92.
"Let us turn our attention now to Fig. [92]. Here we perceive that both the pores and canals are no longer represented white, but black, this color being used to indicate water; in this instance, therefore, water has taken the place of air, or, in other words, the soil is very wet. If we observe our seed a now, we find it abundantly supplied with water, but no air. Here again, therefore, germination cannot take place. It may be well to state here, that this can never occur exactly in nature, because water having the power of dissolving air to a certain extent, the seed a in Fig. [92] is, in fact, supplied with a certain amount of this necessary substance; and, owing to this, germination does take place, although by no means under such advantageous circumstances as it would were the soil in a better condition.
Fig. 93.
Fig. 94.