. Carnegie Institution of Washington publication. THh KMI'.KM) 45 examined the two xylem masses were unequal in size, the largei showing about half a dozen tracheids in cross-section, the smaller two or three. Whether the two protoxylems are ultimately joined hy intermediate tracheal tissue, so as to form a continuous plate, as in the older roots of the adult plant, can not now be stated, but in no cases examined was this true, and it is not unlikely that in the primary root the two xylem masses are permanently separated. The cells of the foot, as usual, are more or less papillate where they a
. Carnegie Institution of Washington publication. THh KMI'.KM) 45 examined the two xylem masses were unequal in size, the largei showing about half a dozen tracheids in cross-section, the smaller two or three. Whether the two protoxylems are ultimately joined hy intermediate tracheal tissue, so as to form a continuous plate, as in the older roots of the adult plant, can not now be stated, but in no cases examined was this true, and it is not unlikely that in the primary root the two xylem masses are permanently separated. The cells of the foot, as usual, are more or less papillate where they arc in contact with the tissue of the gameto- phyte. Ihev early become infected with the endophvte, which probably makes its entrance from the prothallial tissue, and not from the outside. This point, however, is not perfectly clear. The infected area follows the growth of the young root, but leaves the apical tissues free. In O. moluccanum the leaf is the first part of the young sporophyte to develop. In the larger embryos the leaf forms a conical body, merging into a nearly globular basal portion, which is the foot, and within this, probably near the junction of the epibasal and hypobasal halves of the embryo, the apical cell of the root is developed. The leaf now shows a definite apical cell, triangular in section and exhibiting a regular segmentation. The inner cells of the segments form the axial strand of tissue, which is continued through the embryo into the root. The limits of the two. Fig. 27. A. Section of petiole of cotyledon of 0. moluccanum, B. Section of young root. C. Vascular bundle of median region of young sporophyte. D. Vascular bundle of primary root. E. Vascular bundle of primary root of 0. pendulum; eti, endodermis. primary organs, the leaf and the root, remain quite indistinguishable. The central tegion, which remains surrounded by the prothallial tissue, is somewhat larger in diameter and the whole of this functions as a foot, although it is composed in p
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Keywords: ., bookauthorcarnegie, bookcentury1900, bookdecade1910, bookyear1911
