. Lectures on the evolution of plants. Botany; Plants. MOSSES AND LIVEEWOKTS 109 the sporophyte in Riccia is very simple, recalling that of Coleochsete (Fig. 10, C) among the algae, and there is no difficulty in understanding how a sporophyte of the type of that in Riccia may have originated from that of Fig. 28 (Development of the sporophyte in Hepaticse). — A, yonng em- bryo-sporophyte of Targionia ; i, ii, the first division walls in the fertil- ized egg; B, longitudinal section of the young sporophyte of Riccia, in- cluded within the archegonium, ar; all of the cells, except


. Lectures on the evolution of plants. Botany; Plants. MOSSES AND LIVEEWOKTS 109 the sporophyte in Riccia is very simple, recalling that of Coleochsete (Fig. 10, C) among the algae, and there is no difficulty in understanding how a sporophyte of the type of that in Riccia may have originated from that of Fig. 28 (Development of the sporophyte in Hepaticse). — A, yonng em- bryo-sporophyte of Targionia ; i, ii, the first division walls in the fertil- ized egg; B, longitudinal section of the young sporophyte of Riccia, in- cluded within the archegonium, ar; all of the cells, except a single peripheral layer, produce spores ; C, longitudinal section of the young sporophyte of Sphserocarpus; only the upper part produces spores, the lower half forming an organ of absorption, the foot, /; D, a similar section of the embryo of Anthoceros; the nucleated cells represent the arcbesporium or sporogenous tissue; E, cross-section of an older sporophyte of Anthoceros, showing the small amount of sporogenous tissue, sp; P, section through a spore-tetrad of Fossombronia longiseta; only three of the four spores show; G, a ripe spore of the same species; H, an elater. The first result of fertilization is the formation of a cellulose membrane about the egg, which thus is trans- formed into a spore directly comparable to the resting- spore of such an alga as CEdogonium. Here, however, instead of remaining at rest for a long period, it ger- minates at once. It first divides by a transverse wall. 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, London, The Macmillan company


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Keywords: ., bookcentury1900, bookdecade, booksubjectbotany, booksubjectplants