. Un manuel de botanique cryptogamique. Les cryptogames. 30 cryptogames vasculaires pédicelles plus robustes, et Ari^e à partir de l'apex de l'columel. Dans la fonna- tion de l'megasporanges pédicelles de la division cellulaire longitudinale, de même que transversal. Le mode de formation des spores à l'intérieur de chaque genre de sporange a déjà été décrite en termes généraux, après la séparation d'une seule couche externe de cellules qui se développe dans la paroi de l'sporange. La soixante-quatre spores de micro- semblent être éliminés sans aucun arrangement dans la cavité du microsporange. Un gros noyau

• Contributeur: The Book Worm / Alamy Banque D'Images
• ID de l’image: RE3NBD
• Taille du fichier: 7,1 MB (406,8 KB Téléchargement compressé)
• Autorisations: Modèle - non | Propriété - non
• Dimensions: 1594 x 1567 px | 27 x 26,5 cm | 10,6 x 10,4 inches | 150dpi

Informations supplémentaires

Cette image appartient au domaine public, ce qui signifie que le droit d’auteur a expiré ou que le titulaire du droit d’auteur a renoncé à ses droits. Les frais facturés par Alamy couvrent l’accès à la copie haute résolution de l’image.

Cette image peut avoir des imperfections car il s’agit d’une image historique ou de reportage.

. A handbook of cryptogamic botany. Cryptogams. 30 VASCULAR CRYPTOGAMS stouter pedicels, and ari^e from the apex of the columel. In the fonna- tion of the pedicels of the megasporanges longitudinal cell-division takes place, as well as transverse. The mode of formation of the spores within each kind of sporange has already been described in general terms, after the preliminary separation of a single external layer of cells which develops into the wall of the sporange. The sixty-four micro- spores appear to be disposed without any arrangement in the cavity of the microsporange. A large nucleus lies at the end of the megaspore which is nearest the apex of the sporange. Before fertilisation both kinds of sporange become detached from their pedicels, and are carried. Fig. i2.—yias?.x^oiAzollaCaroliniana'Wi. (X240). (After Strasburger.) up to the surface of the water in the spring by the surrounding masses of Algae. The epi spore then splits above the apex of the megaspore into three lobes, between which the emerald-green prothallium forces itself, and impregnation is effected. In Azolla the epispore assumes a still more striking form. In the microsporanges it has the appearance of a large-celled tissue, and breaks up into two or more spherical masses called massulm, each of which envelops a number of microspores, and has a distinct coat. In some species, but not in all, the surface of these masses is covered with hair-like appendages, barbed at the apex, the glochids, by means of which, after emerging from the sporange, and when floating on the surface of the water, they attach themselves to the. 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 work.. Bennett, Alfred W. (Alfred William), 1833-1902; Murray, George Robert Milne, 1858-. London, New York, Longmans, Green, and Co.

Recherche dans la banque de photos par tags

• bookcentury1800
• bookdecade1880