Text-book of botany, morphological and physiological . and internal structure of the sporogonium are very differentin the different groups. In the Anthoceroteae it is when mature an elongated two-valved pod projecting from the thallus. In the Riccieae it is a thin-walled ballentirely filled with spores, and, together with the calyptra, depressed in the the Marchantieae it is a shortly-stalked ball enclosing elaters as well as spores,and, after it has broken through the calyptra, bursting irregularly or opening by acircular fissure and detaching an operculum. In the Jungermannieae it
Text-book of botany, morphological and physiological . and internal structure of the sporogonium are very differentin the different groups. In the Anthoceroteae it is when mature an elongated two-valved pod projecting from the thallus. In the Riccieae it is a thin-walled ballentirely filled with spores, and, together with the calyptra, depressed in the the Marchantieae it is a shortly-stalked ball enclosing elaters as well as spores,and, after it has broken through the calyptra, bursting irregularly or opening by acircular fissure and detaching an operculum. In the Jungermannieae it ripens evenwithin the calyptra, but breaks through it and appears as a ball borne upon along slender stalk ; the receptacle consists, as in the Marchantieae and Riccieae,when ripe, of a single layer of cells, but separates cross-wise into four lobes, towhich the elaters remain attached. The elaters are, as in the Marchantieae, longfusiform cells, the delicate colourless outer layer of which is thickened within byfrom one to three brown spiral Fig. 214 bis.—First stafje of development of the archesjo-nium of Andrenfa (after Kiihn) ; A terminal arrhejroniumarising from the apical cell of the shoot; b b the younjjcstleaves ; B after the formation of the central cell and stig-matic cell; C transverse section of the young ventralportion. HEP A TICM. 301 The sporogonium also originates in different ways. The fertilised oosphereis always first divided in the archegonium into two cells, the upper of which,facing the neck, forms the growing apical cell; but this divides in very differentways in the different groups:—in Anthoceros by oblique walls inclined in fourdirections; in the IMarchantiese and Ricciese by walls inclined alternately in twodirections; while the sporogonium of the Jungermanniese contains, even in its veryearliest stage, four apical cells lying beside one another like octants of a sphere,
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectbotany, bookyear1875
