The word which is translated "grass" [Hebrew script] means in reality, any fresh sprout. Now it is remarkable that Moses specifies three kinds of vegetation, with regard to two of which it is noted that they produce seed, while nothing is said of the seed of the remaining class. Grass too, is really a herb bearing seed, and, as such would be included in the second class, and there would have been no occasion, to mention it separately. It would appear then that the first class consisted of seedless plants, i. e. of the cryptogamia. This conclusion is strengthened when we turn to verses 29 and 30. If the word [Hebrew script] were correctly translated "grass," we should certainly expect to find it in those verses, since the grasses contribute more to the food of both man and beast, than all the other herbaceous plants put together. This omission then, is an indication that the word, as used in this chapter, denotes a class of plants which are not commonly employed for food, and this condition also is fulfilled in the cryptogamia.
There are then four special points in this period, of which two seem to correspond with the Mosaic record, while the other two are unnoticed in it. The two points of correspondence are the upheaval of the dry land, and the prevalence of a very abundant and luxuriant Flora. As in the case of the fifth and sixth days, the words used with reference to land plants seem to denote a period of remarkable development, rather than the first appearance. The two points unnoticed are the beginnings of animal and vegetable life. In the case of animal life the omission has already been accounted for. The beginning of vegetable life was probably contemporaneous with that of animal life, for each is necessary to the other, since the food of the animal must be prepared by the vegetable, and after being used by the former returns to a state in which it is fitted for the nourishment of the latter. As animal life commenced in the ocean, so in all probability did vegetable life, though no certain traces of it are found in the earliest rocks; but this is easily accounted for by the very perishable character of the simpler forms of algae. Like the earliest animals, the first algae were probably microscopic plants, and the omission of any mention of them was therefore inevitable.
One characteristic of cryptogamic vegetation is important for its bearing on the work of the fourth day. Almost all the phanerogamic plants are dependent for their development upon the direct light and heat of the sun. Deprived of these they either perish entirely, or make an unhealthy growth, and produce little or no fruit. But the cryptogamia, in general, thrive best when they are protected from the direct rays of the sun. They nourish in a diffused light, and with abundant atmospheric moisture. And so we find them at this time doing what seems a very important work in the progress of the world. By taking up and decomposing the excess of carbonic acid which at this time probably existed in the atmosphere, they at once purified that atmosphere, and rendered it fit for the respiration of more highly organized creatures, and laid up in the earth an invaluable store of fuel for the future use of man. The other orders of vegetation seem to have existed in very small proportions at this time, and only in their lower forms. As the conditions of the earth changed, the cryptogamia seemed to have dwindled away, while higher forms of vegetation asserted their supremacy. It is not, however, improbable that a special development at a much later period is indicated by the mention in the second chapter of the formation of the garden of Eden.
SECTION 7. THE FOURTH DAY.
"And God said, Let there be luminaries in the firmament of heaven to divide between the day and the night, and let them be for signs and for seasons, and for days and for years.
"And let them be for luminaries in the firmament of heaven to give light upon the earth; and it was so.
"And God made the two luminaries, the great ones; the luminary, the great one, to rule over the day, and the luminary, the small one, to rule over the night, and also the stars.
"And God gave them in the firmament of heaven to give light upon the earth.
"And to rule over the day and over the night, and to divide between the light and between the darkness; and God saw that it was good.
"And there was evening, and there was morning, a fourth day."