Botanique élémentaire . nddecreases de 12-6 h, tandis que le tournesol avec greatestbefore il est 10 heures, quand il commence à diminuer. La température du sol est l'un des plus importants facteurs externes influent sur l'activité d'ing-pression racinaire. Fig. 45. Expérience toshow pression racinaire(Detmer). Chapitre IV. La transpiration, OU LA PERTE D'EAU. BYPLANTS 68. Nous devons maintenant demander si toute l'eau qui est pris qui sorte upin suffit en fait de turgescence est utilisé dans theelaboration de nouveaux matériaux de construction. Nous remarquons quand aleaf ou shoot est coupée à partir d'une plante, à moins qu'il n'est ke

• Contributeur: The Reading Room / Alamy Banque D'Images
• ID de l’image: 2AJEGC4
• Taille du fichier: 7,1 MB (258,4 KB Téléchargement compressé)
• Autorisations: Modèle - non | Propriété - non
• Dimensions: 2405 x 1039 px | 40,7 x 17,6 cm | 16 x 6,9 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.

Elementary botany . nddecreases from 12-6 p.m., while with the sunflower it is greatestbefore 10 a.m., when it begins to decrease. Temperature ofthe soil is one of the most important external conditions affect-ing the activity of root pressure. Fig. 45. Experiment toshow root pressure(Detmer). CHAPTER IV. TRANSPIRATION, OR THE LOSS OF WATER BYPLANTS. 68. We should now inquire if all the water which is taken upin excess of that which actually suffices for turgidity is used in theelaboration of new materials of construction. We notice when aleaf or shoot is cut away from a plant, unless it is kept in quitea moist condition, or in a damp, cool place, that it becomes flac-cid, and droops. It wilts, as we say. The leaves and shoot losetheir turgidity. This fact suggests that there has been a loss ofwater from the shoot or leaf. It can be readily seen that thisloss is not in the form of drops of water which issue from the cutend of the shoot or petiole. Whajt then becomes of the water inthe cut leaf or shoot ?. Fig. 46.To show loss of water from leaves, the leaves just covered. 69. Loss of water from excised leaves.—Let us take a handfulof fresh, green, rather succulent leaves, which are free from 35 3$ PHYSIOLOGY. water on the surface, and place them under a glass bell jar, whichis tightly closed below but which contains no water. Now placethis in a brightly lighted window, or in sunlight. In the courseof fifteen to thirty minutes we notice that a thin film of moistureis accumulating on the inner surface of the glass jar. After anhour or more the moisture has accumulated so that it appears inthe form of small drops of condensed water. We should set upat the same time a bell jar in exactly the same way but whichcontains no leaves. In this jar there is no condensed moistureon the inner surface. We thus are justified in concluding that

Recherche dans la banque de photos par tags

• bookauthoratk
• bookcentury1900
• bookdecade1900
• booksubjectbotany