. Ein Lehrbuch der Botanik für Hochschulen und Universitäten ... Botanik. 624 Ökologie tective Layer. In der Regel der Behälter nicht Entlastung der Ex-terior, aber in Eukalyptus und in verschiedenen Rutaceae Es sind Zellen, die nach einer Zeit Bruch an einem bestimmten Ort oder entlang der Wände, so dass die Sekrete weg zu führen. In einigen Fällen, wie bei Peperomia und in verschiedenen Lebermoose, gibt es einzelne Zellen, die schleimstoffe (Abbn. 745, 928). Die Stoffe durch interne Drüsen abgesondert ähneln denen Se-creted durch glanduläres Haare, und ebenso oft Wohlriechenden. Die rdle von Ölen, Harzen und muci

• Bildanbieter: Central Historic Books / Alamy Stock Foto
• Bild-ID: PG20XD
• Dateigröße: 7,2 MB (273,5 KB Komprimierter Download)
• Freigaben (Releases): Model - nein | Eigentum - nein
• Format: 1748 x 1430 px | 29,6 x 24,2 cm | 11,7 x 9,5 inches | 150dpi

Weitere Informationen

Dieses Bild ist ein gemeinfreies Bild. Dies bedeutet, dass entweder das Urheberrecht dafür abgelaufen ist oder der Inhaber des Bildes auf sein Urheberrecht verzichtet hat. Alamy berechnet Ihnen eine Gebühr für den Zugriff auf die hochauflösende Kopie des Bildes.

Dieses Bild kann kleinere Mängel aufweisen, da es sich um ein historisches Bild oder ein Reportagebild handel

. A textbook of botany for colleges and universities ... Botany. 624 ECOLOGY tective layer. Usually the reservoir does not discharge to the ex- terior, but in Eucalyptus and in various Rutaceae there are cover cells, which after a time rupture at a definite spot or along the walls, allowing the secretions to pass off. In some cases, as in Peperomia and in various liverworts, there are single cells that secrete mucilage (figs. 745, 928). The substances secreted by internal glands resemble those se- creted by glandular hairs, and likewise are often odoriferous. The rdle of oils, resins, and mucilage. — But little is known concern- ing the r61e of oils, resins, and mucilage, though speculation along this line has been abundant. Wax coats previously have been seen to rep- resent waste products that are of incidental value in protect- ing against excessive transpira- tion (p. 570). A similar theory has been proposed concerning excreted volatile oils, on the ground that they absorb heat in large amount, but it is most unlikely that these oils are present in sufiicient abundance to check transpiration. Simi- larly improbable is the common theory that sticky glandular hairs, which are especially abun-. FlG. 917. — An internal oil gland (a) in the orange (Citrus Aurantium); o, oil drops; highly magnified. — From TscHIECH. dant on floral stems, are of value in keeping crawling insects away from the flowers, or the theory that various secretions which are unpalatable or even poisonous (as in Primula) may lead to the better preservation of plant species from grazing animals. Somewhat more probable but scarcely authenticated are the r61es cbmmonly ascribed to slime in water plants, such as protection from snails and other water herbivores and from water currents. In gelatinous lichens and in am- phibious algae, mucilaginous secretions may protect from desiccation. In the economy of aquatic life as a whole, slime plays an important part, since it is a perfect culture medium

Stockbilder mithilfe von Tags suchen

• bookcentury1900
• bookdecade1910
• booksubjectbotany
• bookyear1910