=216. The first leaf of the jack-in-the-pulpit is a simple one.=—The first leaf of the embryo jack-in-the-pulpit is very different in form from the leaves which we are accustomed to see on mature plants. If we did not know that it came from the seed of this plant we would not recognize it. It is simple, that is it consists of one lamina or blade, and not of three leaflets as in the compound leaf of the mature plant. The simple leaf is ovate and with a broad heart-shaped base. The jack-in-the-pulpit, then, as trillium, and some other monocotyledonous plants which have compound leaves on the mature plants, have simple leaves during embryonic development. The ancestral monocotyledons are supposed to have had simple leaves. Thus there is in the embryonic development of the jack-in-the-pulpit, and others with compound leaves, a sort of recapitulation of the evolutionary history of the leaf in these forms. =216=_a_. =Germination of the pea.=—Compare with the bean. Note especially that the cotyledons are not lifted above the soil as in the beans. Compare germination of acorns. Digestion. =216=_b_. =To test for stored food substance in the seedlings studied.=—The pumpkin, squash, and castor-oil bean are examples of what are called oily seeds, since considerable oil is stored up in the protoplasm in the cotyledons. To test for this, remove a small portion of the substance from the cotyledon of the squash and crush it on a glass slip in a drop or two of osmic acid.[16] Put on a cover glass and examine with a microscope. The black amorphous matter shows the presence of oil in the protoplasm. The small bodies which are stained yellow are _aleurone_ grains, a form of protein or albuminous substance. Both the oil and the protein substance are used by the seedling during germination. The oil is converted into an available food form by the action of an enzyme called _lipase_, which splits up the fatty oil into glucose and other substances. Lipase has been found in the endosperm of the castor-oil, cocoanut, and in the cotyledons of the pumpkin, as well as in other seeds containing oil as a stored product. The aleurone is made available by an enzyme of the nature of trypsin. Test the endosperm of the castor-oil bean in the same way. Make another test of both the squash and castor-oil seeds with iodine to show that starch is not present.