They are accompanied by intercellular channels serving for the conduction of oxygen to, and carbon dioxide from, the living cells in the interior of the wood, which would otherwise be cut off from the means of respiration.
This large evaporation, which constitutes the so-called transpiration of plants, takes place not into the external air but into this same intercellular space system, being possible only through the delicate cell-walls upon which it abuts, as the external coating, whether bark, cork or cuticle, is impermeable by watery vapour.
Fumago, Herpotrichia, &c., or, at most, vegetate in the intercellular spaces and anchor itself to the cell-walls, e.g.
In the cortical tissue beneatJI each furrow a wide intercellular space is present running the length of the internode, and called the (C, D, E from Strasburger's Lehrbuch der Bolanik, by permission of Gustav Fischer.) FIG.
The stomata are in direct communication with the ample system of intercellular spaces which is found in the loosely arranged mesophyll (spongy tissue) on that side.
The intercellular spaces are here very narrow channels between the palisade cells.
1, v.), so that the endodermal cells cannot be split apart to admit of the formation of intercellular spaces, and an air-tight sheath is formed round the cylinder.
Intercellular channel representing xylem; ph.
In other cases the reduction goes much further, till the endodermis eventually comes to surround nothing but an intercellular channel formed in place of the stelar tissue.
This may take various forms and may cover the whole of the organ or be localized in special regions; but its cells are always living and are separated by very large intercellular spaces containing air.
The difficulty is solved by the provision of a complete system of minute intercellular spaces which form a continuous series of delicate canals between the cells, extending throughout the whole substance of the plant.
This is secured by the development of much larger intercellular spaces, amounting to lacun~e or passages of very considerable size, which are found ramifying in different ways in their interior.
The entry of gases into, and exit from, the cells, as well as the actual exhalation of watery vapour from the latter, take place in the intercellular space system of which the stomata are the outlets.
Their leaves and, to some extent, their stems have much water-storing tissue and few intercellular spaces.
Benham, the tube, though smaller, and with a but little pronounced funnel, has still an intercellular duct.
It is by no means certain that a hard and fast line can be drawn between intraand intercellular lumina.
In Polynoe the nephridia are short tubes with a slightly folded funnel whose lumen is intercellular, and this intercellular lumen is characteristic of the Polychaetes as contrasted with leeches and Oligochaetes.
These substances may be formed in the cells and given out as a secretion, or they may be formed by an intercellular transformation.
This pigment is usually intracellular, but may be found lying free in the intercellular substance, and is generally in the form of fine granules of a yellowish-brown or brown-black colour.
Cellular activity and oxygen appear to be essential for its development; it is found usually in the cells of certain organs, or it may be deposited in the intercellular tissues.
This is a large group of about 2000 forms. They are all intercellular parasites living mostly on the leaves of higher plants.
Endophytic parasites may be intracellular, when the fungus or its mycelium plunges into the cells and destroys their contents directly (Olpidium, Lagenidium, Sclerotinia, &c.), but they are far more frequently intercellular, at any rate while young, the mycelium growing in the lacunae between the cells (Peronospora, Uredineae) into which it may send short (Cystopus), or long and branched (Peronospora Calotheca) haustoria, or it extends in the middle lamella (Ustilago), or even in the solid substance of the cell-wall (Botrytis).
No sharp lines can be drawn, however, since many mycelia are intercellular at first and subsequently become intracellular (Ustilagineae), and the various stages doubtless depend on the degrees of resistance which the host tissues are able to offer.
The epidermis is continuous except where stomata or spaces bounded by specialized cells communicate with intercellular spaces in the interior of the leaf.
(After Hertwig.) bearing at its free upper end a stiff bristle and running out at its base into a nerve-fibre; (3) concrement-cells, which produce intercellular concretions, so-called oto liths.
At intervals it is interrupted by pores (stomata) leading from the air outside to the system of intercellular spaces below.
The epithem is penetrated by a network of fine intercellular spaces, which are normally filled with water and debouch on one or more intercellular cavities below the epidermis.
A striking feature is the presence of large, radiating intercellular cavities in the cortex, suggesting an aquatic habit.
The leaves have a single main bundle, and in the mesophyll are four longitudinal series of large intercellular spaces separated by transverse diaphragms. The sporangia, which are situated singly on the adaxial surface of the leaves, between their insertion on the stem and the ligule, arise from a considerable number of epidermal cells.
Kolb, is that a peculiar fermentation is set up under the influence of heat and moisture, resulting in a change of the intercellular substance - pectose or an analogue of that body - into pectin and pectic acid.
Certain species are regularly found in the intercellular spaces of higher plants; such are species of Nostoc in the thallus of Anthoceros, the leaves of Azolla and the roots of Cycads.
In all these cases we have a duct which has a usually wide, always intercellular, lumen, generally, if not always, ciliated, which opens directly into the coelom on the one hand and on to the exterior of the body on the other.
This system of intercellular spaces, extending throughout the plant, constitutes a reservoir, charged with an atmosphere which differs somewhat in its composition from the external air, its gaseous constituents varying from time to time and from place to place, in consequence of the interchanges between itself and the protoplaste.
These plastids are especially charged with the duty of manufacturing carbohydrates from the carbon dioxide which the air contains, and which is absorbed from it after it has entered the intercellular passages and has so reached the cells containing the plastids.