. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. 3S6 MOSSES AND FERt/S CHAP. tracts until it becomes oblong, and in close contact with the egg nucleus, in some cases looking as if it had penetrated the egg nucleus as it does in Onoclea (Shaw (2)). The process is a slow one, and in one case twenty-four hours after the entrance of the spermatozoid the two nuclei were still recognisable. Finally they are completely fused, and a single nucleus, with usually, perhaps always, two nucleoli is seen. No sign of a separation of the chromosomes of the
. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. 3S6 MOSSES AND FERt/S CHAP. tracts until it becomes oblong, and in close contact with the egg nucleus, in some cases looking as if it had penetrated the egg nucleus as it does in Onoclea (Shaw (2)). The process is a slow one, and in one case twenty-four hours after the entrance of the spermatozoid the two nuclei were still recognisable. Finally they are completely fused, and a single nucleus, with usually, perhaps always, two nucleoli is seen. No sign of a separation of the chromosomes of the copulating nuclei was observed. The Embryo The first division of the ovum is the same with respect to the archegonium as in Onoclea, i. e., the basal wall is parallel. Fio. ipS.^A, Vertical section of an eight-celled embryo of O. Claytoniana, X260. Median longitudinal section of an older embryo of the same species, X260; C, two transverse sections of a somewhat younger embryo of O. cinnamomea, X260; St, stem apex; L, cotyledon; r, primary root; F, foot. with its axis; but the quadrant wall is also parallel with this instead of transverse, although its position with reference to the axis of the prothallium is the same; so that the embryo-quad- rants, and the organs derived from them, are situated like those of the polypodiaceous embryo, with reference to the prothal- lium, but not to the Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Campbell, Douglas Houghton, 1859-1953. New York, The Macmillan Company;
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