. Class-book of botany: being outlines of the structure, physiology and classification of plants; with a flora of the United States and Canada. Botany; Plants; Plants. first expands into a proper cell, and is usually attached to the wall of the sac near the micropyle. It then di- vides itself transversely, becoming two cells; tho upper tlongates either with or without subdivision, forming a filament (suspensor); the lower cell enlarges by subdi- vision, first spherically, and afterwards the little mass begins to take form according to the species, showing cotyledons, plumule, etc., until fully
. Class-book of botany: being outlines of the structure, physiology and classification of plants; with a flora of the United States and Canada. Botany; Plants; Plants. first expands into a proper cell, and is usually attached to the wall of the sac near the micropyle. It then di- vides itself transversely, becoming two cells; tho upper tlongates either with or without subdivision, forming a filament (suspensor); the lower cell enlarges by subdi- vision, first spherically, and afterwards the little mass begins to take form according to the species, showing cotyledons, plumule, etc., until fully developed into tho embryo. 759. Schleiden's view. Owing to the ex- treme difficulty of observation in this minnto field, different views of this process have been advanced. That of Schleidcn should not be overlooked. He maintains that the end of the pollen tube actually penetrates the sac and itself becomes the embryonic cell. The pollen grain is in this view the primitive cell, and is itself quickened into development by the contents of COS, Growth of the emtryo * , in Hippurls vulgaris. The ftrti-thG embryo Sac. tizod cell has divided itsell in- Hon t? to several, of which c, O, con- l6°- FERTILIZATION IN THE CONIFERS. etitute the suspensor attached Where no style or stigma exists, as in the Coni- to the apex of the sac; a, em-f ^ ]len fal]s djreetly iato the micropyle bryo dividing i»to 2, then into ' l J rJ 4 cells. of the naked ovule and its tubes settle into the tissue of the nucleus. 761. Chemical changes in germina- tion. The ovule matures with the com- pletion of the embryo, and passes into the fixed state of the seed in which the embryo sleeps. A store of nutritive matter, starch, gluten, etc., is thought- fully provided in the seed for the use of the young plant in germination, until its root has gained fast hold of the soil. 762. The changes which occur in the seed at the recommencement of „. 609, Ovule of Viola tricolor, showing; growth, are simply such as are
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