41. In Iris (Fig. 58, 59) the embryo in the seed is a small cylinder at one end of the mass of the albumen, with no apparent distinction of parts. The end which almost touches the seed coat is caulicle, the other end belongs to the solitary cotyledon. In germination the whole lengthens (but mainly the cotyledon) only enough to push the proximate end fairly out of the seed; from this end the root is formed, and from a little higher the plumule later emerges. It would appear therefore that the cotyledon answers to a minute leaf rolled up, and that a chink through which the plumule grows out is a part of the inrolled edges. The embryo of Indian Corn shows these parts on a larger scale and in a more open state (Fig. 66-68). There, in the seed, the cotyledon remains, imbibing nourishment from the softened albumen, and transmitting it to the growing root below and new-forming leaves above. [Illustration: Fig. 60. Section of an Onion seed showing the slender and coiled embryo in the albumen, moderately magnified. 61. Seed of same in early germination.] [Illustration: Fig. 62. Germinating Onion, more advanced, the chink at base of cotyledon opening for the protrusion of the plumule, consisting of a thread-shaped leaf. 63. Section of base of Fig. 62, showing plumule enclosed. 64. Section of same later, plumule emerging. 65. Later stage of 62, upper part cut off. 66. A grain of Indian Corn, flatwise, cut away a little, so as to show the embryo, lying on the albumen which makes the principal bulk of the seed. 67. A grain cut through the middle in the opposite direction, dividing the embryo through its thick cotyledon and its plumule, the latter consisting of two leaves, one enclosing the other. 68. The embryo taken out whole; the thick mass is the cotyledon, the narrow body partly enclosed by it is the plumule, the little projection at its base is the very short radicle enclosed in the sheathing base of the first leaf of the plumule.] [Illustration: Fig. 69. Grain of Indian Corn in germination, the ascending sprout is the first leaf of the plumule, enclosing the younger leaves within, at its base the primary root has broken through. 70. The same, advanced; the second and third leaves developing, while the sheathing first leaf does not further develop.]