Recueil des travaux botaniques néerlandais . le1. Micropylar région, sarcotesta with mucilage cavities, place wherethe sclerotesta begins to differentiate is dotted, the micropyle is seen asa triangular fissure. 2. Portion of 1, around the micropyle , 4, 5 and 6 transverse sections through lower parts, the anglesgradually dy ont. marked on the sclerotesta, their number being two, threeor four. In very young ovules no trace of them is to 261 be seen, only when they hâve reached a rather considérablesize, the stony coat begins to differentiate, and herewiththe ribbing occurs. The firs
Recueil des travaux botaniques néerlandais . le1. Micropylar région, sarcotesta with mucilage cavities, place wherethe sclerotesta begins to differentiate is dotted, the micropyle is seen asa triangular fissure. 2. Portion of 1, around the micropyle , 4, 5 and 6 transverse sections through lower parts, the anglesgradually dy ont. marked on the sclerotesta, their number being two, threeor four. In very young ovules no trace of them is to 261 be seen, only when they hâve reached a rather considérablesize, the stony coat begins to differentiate, and herewiththe ribbing occurs. The first indication of it is to be seenon transverse sections at the micropyle. In a young stagethis is entirely round, but when the ovule has attained adiameter of about half a centimeter, it looks like a longstretched fissure or ike a triangle with collapsed sides(fîg. 5). Sections made lowerdown, show clearly theplaces of the ribs. In sections close below the micropyle, at the places ofthe ribs, an elongation of the cells is to be seen as a. Fig. 6. Ginkgo biloba, transverse section below the micropyle, onthe place of the rib ; an elongation of the cells is to be seen. lengthening of the fissure, giving the impression ofa suture (flg. 6). À resarch has been made by Àffourtit and LaRivière concerning the ribbing of the seeds (1). Theirregularity of those ribs has struck them and they madea statistic of their occurrence with the help of a greatnumber of seeds, originating from the same tree fromwhich my material was collected. Trom the llZexamined 262 seeds. there vvere 47 with two, 65 with three and 5 withfour ribs. At the end of their note they compare the seeds ofGinkgo with those of Trigonocarpus Shorensis, and say:„Since in Ginkgo, however. no valves occur — the stonycoat lacking fissures at the place of the ribs — and asvascular bundles are absent from the sarcotesta, thoseseeds cannot, as it seems to us, be compared with theseeds hère M described (p. 594). On ac
Size: 1779px × 1405px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectplants, bookyear1904
