. Dansk botanisk arkiv. Plants; Plants -- Denmark. F. Børgesen : Rhodophyceæ of the Danish W. Indies. 205 often comes very near to true dichotomy, . but when exam- ined more carefully one finds that one of the young cells is always formed a little earlier and is larger than the other (comp. Fig. 192 c, d). Lewis, too, (1. c. p. 250) considers the ramification to be lateral, "true dichotomy appears never to occur". In Griffithsia corallina Kylin^) found the ramification to be lateral, and Oltmanns says in Handbuch the same for Griffithsia on the whole. As pointed out by Lewis, and acc
. Dansk botanisk arkiv. Plants; Plants -- Denmark. F. Børgesen : Rhodophyceæ of the Danish W. Indies. 205 often comes very near to true dichotomy, . but when exam- ined more carefully one finds that one of the young cells is always formed a little earlier and is larger than the other (comp. Fig. 192 c, d). Lewis, too, (1. c. p. 250) considers the ramification to be lateral, "true dichotomy appears never to occur". In Griffithsia corallina Kylin^) found the ramification to be lateral, and Oltmanns says in Handbuch the same for Griffithsia on the whole. As pointed out by Lewis, and according to my material also, by far the greater part of the specimens were tetrasporic. The tetrasporangia form a ring at the upper end of the cell (Fig. 192 a). As a rule three of them are found together, one of them placed termin- ally, the others later- ally upon a basal cell (Fig. 193 a, d); the development of this tetrasporic branch is given by Lewis. On the outside this tetrasporic ring is pro- tected by a circle of short, thick somewhat inwardly curved cells, together forming a kind of involucrum (Fig. 192 a). As pointed out by Lewis these cells grow up immediately from the cells in the main filaments (Fig. 193 a). In Griffithsia corallina Kylin (1. c, p. 116), on the other hand, describes and beautifully delineates the protecting cells as excrescences from the basal cell in the tetrasporic branch. A cell is cut off from the basal cell, and this cell is divided into two cells, the uppermost being very enlarged and becoming a protecting cell. This way ') Kylin, H., Die Entwicklungsgeschichte von Griffithsia coraUina ( Ag. (Zeitschr. f. Botanik, 8. Jahrg., 1916, p. 99).. Fig. 192. Griffithsia globifera (Harv.) J. Ag. a, part of a tetrasporic plant, b, a dwarf shoot. c and d, upper ends of main filaments showing ramification, (a, about 25: 1; b, about 250 :1); c and d, about 30 :1).. Please note that these images are extracted from scanned page images that may have
Size: 1405px × 1779px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectio, bookdecade1910, booksubjectplants
