The body of the soul develops in four different ways according to its different sources. One kind of body, that of the trees and plants, sprouts from the earth; the second kind of body grows from perspiration, as with flies, germs and bugs; the third kind of body develops from eggs; and the fourth develops from an embryo. This verse indicates that after emulsification of the ovum and sperm, the body gradually develops either into a lump of flesh or into an egg, as the case may be. In the case of birds it develops into an egg, and in the case of animals and human beings it develops into a lump of flesh.