The structure & development of the mosses and ferns (Archegoniatae) . Fig. 97.—Funat-za hygro7)ieti-ica {Slhth.). A, Longitudinal section of a sporogonium showing the firstdifferentiation of its parts, Xabout 96 ; B, the upper part of the same, x6oo ; r marks the hmitsof the theca and operculum ; C, basal part of the capsule of the same, x6oo. The intercellularspaces are beginning to form ; ar, archesporium ; col, columella. 200 MOSSES AND FERNS CHAP. succession is the same, except for the formation of the arche-sporium. Almost as soon as the capsule is recognisable, thefirst indication of the
The structure & development of the mosses and ferns (Archegoniatae) . Fig. 97.—Funat-za hygro7)ieti-ica {Slhth.). A, Longitudinal section of a sporogonium showing the firstdifferentiation of its parts, Xabout 96 ; B, the upper part of the same, x6oo ; r marks the hmitsof the theca and operculum ; C, basal part of the capsule of the same, x6oo. The intercellularspaces are beginning to form ; ar, archesporium ; col, columella. 200 MOSSES AND FERNS CHAP. succession is the same, except for the formation of the arche-sporium. Almost as soon as the capsule is recognisable, thefirst indication of the operculum or lid becomes half-way between the extreme apex of the sporogoniumand the top of the apophysis, a shallow depression is noticedextending completely round the capsule and separating thesharply conical apex from the part below. An examination ofa longitudinal section at this point shows that at the point ofseparation the epidermal cells of the opercular portion are. Fig. 98.—Longitudinal section of an older capsule of F. hygroineti-ica ; /, intercellular spaces ;5/, archesporlum ; r, cells between operculum and theca, X 525. much narrower than those immediately below. Examiningthe tissues farther in, the archesporium is seen to extend onlyto a point opposite the base of the operculum, and the same istrue of the row of large cells where the air-space is a similar section is made through an older capsule (Fig. 98)it is evident at once that the enlargement takes place mainlybelow the junction of the operculum, and there is also a similarbut less pronounced increase in diameter in the operculumitself; but there is a narrow zone at the junction of the oper-culum and capsule, where the epidermal cells increase but VII THE BR VINE^ 201 little in depth, while those above this point become very muchlarger and project beyond them. This narrow zone of cellsmarks the point where when ripe the operculum becomesdetached. The latter, up to the time
Size: 1501px × 1664px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, bookidstructuredev, bookyear1895
