The Physiology of StomataCarnegie Institution of Washington, 1908 - 142 pagina's |
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Pagina 10
... plastids of the guard - cells are numerous and very faintly green . The size of the plastid varies with the amount of contained starch , and this doubtless modifies the optical effect of the chlorophyll upon the eye . Even when the ...
... plastids of the guard - cells are numerous and very faintly green . The size of the plastid varies with the amount of contained starch , and this doubtless modifies the optical effect of the chlorophyll upon the eye . Even when the ...
Pagina 11
... cells are of the very generally distributed type , with wavy outlines , and both the ... guard - cell wall affects chiefly the lower wall . The hinge which , in oco ... plastids , even when they are. FIG . 4. - Stoma of Verbena ciliata in ...
... cells are of the very generally distributed type , with wavy outlines , and both the ... guard - cell wall affects chiefly the lower wall . The hinge which , in oco ... plastids , even when they are. FIG . 4. - Stoma of Verbena ciliata in ...
Pagina 93
... GUARD - CELLS . * NORMAL DIURNAL CHANGES IN THE CONTENTS OF THE GUARD ... plastids and their amyloid inclosures , and in part on account of one's ... cell is at its maximum . The whole of each plastid , when iodine is applied , colors ...
... GUARD - CELLS . * NORMAL DIURNAL CHANGES IN THE CONTENTS OF THE GUARD ... plastids and their amyloid inclosures , and in part on account of one's ... cell is at its maximum . The whole of each plastid , when iodine is applied , colors ...
Pagina 94
... guard - cell . Their size , together with their number , give the interior of the cell a crowded appearance which ... plastids come to be comparatively insignificant in size , and often lie in profile on the periphery of the cell , as ...
... guard - cell . Their size , together with their number , give the interior of the cell a crowded appearance which ... plastids come to be comparatively insignificant in size , and often lie in profile on the periphery of the cell , as ...
Pagina 94
... guard - cell . Their size , together with their number , give the interior of the cell a crowded appearance which ... plastids come to be comparatively insignificant in size , and often lie in profile on the periphery of the cell , as ...
... guard - cell . Their size , together with their number , give the interior of the cell a crowded appearance which ... plastids come to be comparatively insignificant in size , and often lie in profile on the periphery of the cell , as ...
Overige edities - Alles bekijken
Veelvoorkomende woorden en zinsdelen
a. m. Experiment absence absolute alcohol abundant in guard-cells afternoon amount of starch Ampelopsis appears April 24 behavior bell-jar Brown & Escombe carbon dioxid cent chlorophyll closure CO₂ conclusion condition constant curve dark room diastase diffused light diffusion capacity dimensions etiolated evidence Experimental exposure ferment Fouquieria splendens Francis Darwin Galtonia Grams guard-cell plastids illumination increase induced rhythm July July 15 Kohl Kohl's leaf Leitgeb maximum opening mean measurements ment method micra plate minutes normal observed occur ocotillo period photosynthesis physiological piece of epidermis placed in dark plant potometer present rate of transpiration ratio reduced regard relative humidity secondary leaves small amount Starch absent Starch abundant starch in chlorenchyma starch in guard-cells Stomata of Verbena stomatal activity stomatal movement stomatal openings stomatal pore TABLE temperature tion tissue transpiration rate transverse measurement turgor Verbena ciliata water-vapor widely open Width wilting
Populaire passages
Pagina 32 - ... herbaceous leaf illustrates in a striking manner all the physical properties of a multiperforate septum. Regarded from this point of view it is shown that the stomatic openings and their adjuncts constitute even a more perfect piece of mechanism than is required for the supply of carbon dioxide for the physiological needs of the plant, and instead of expressing surprise at the comparatively large amount of the gas which an assimilating leaf can take in from the air, we must in future rather wonder...
Pagina 32 - ... diaphragm, whose apertures are so far reduced in size as to materially interfere with the mass movement of the diffusing substance. A section of the paper is devoted to the application of these new observations to the processes of gaseous and liquid diffusion in living plants, and it is pointed out that the structure of a typical herbaceous leaf illustrates in a striking manner all the physical properties of a multiperforate septum. Regarded from this point of view it is shown that the stomatic...
Pagina 86 - He concluded, however, that xerophytic leaf structure (of the hardy evergreens) is not always incompatible with abundant transpiration, but sometimes exists only for use in emergencies, to protect the plant from injurious loss of water.
Pagina 32 - ... possess all the remarkable properties which had been anticipated. The material used for the septa was very thin celluloid, which was perforated at regular intervals with holes of about 038 mm. in diameter. Details of a number of experiments with such diaphragms are given, in which it is shown that they may be so arranged as to produce but little obstructive influence on the diffusive flow of a gas when the total area of the apertures amounts only to about 10 per cent, of the area of the septum,...
Pagina 58 - ... under the microscope but the rapid closing of the stoma in the case of plants standing in the shade suggests that possibly the balance between the tensions is so delicate that the least disturbance of the equilibrium, as in making the sections for examinations, may bring about the closing. It is also possible that, owing to the activity of the secreting cells and the accumulation of intracellular water, the stomata may open at varying periods and after the escape of the vapor close again.
Pagina 65 - ... conclusion that no serious error was being introduced through the fluctuations of the hmidity. A few measurements are given in Table IV., of the transpiration of plants in the dark. Occasionally there is apparent a rhythm corresponding to the daily periodicity, but on the other hand it not unfrequently happens that there may be an irregular decline from the start or the curve may be characterized by a rise or fall without reference to the period of the day. I have noticed on several occasions...
Pagina 125 - My conclusion is, therefore, that the presence or absence of CO2 has no direct influence on stomata, and that, physiologically, they are not at all dependent upon photosynthetic processes within the guard-cells. If this is true, the guard-cell is set off as distinct physiologically from the chlorenchymacell. . . . The mere fact that stomata open in the absence of CO2 shows conclusively that the movement is not directly connected with photosynthetic activity, even if the process takes place normally...
Pagina 125 - ... is, therefore, that the presence or absence of CO2 has no direct influence on stomata, and that, physiologically, they are not at all dependent upon photosynthetic processes within the guard-cells. If this is true, the guard-cell is set off as distinct physiologically from the chlorenchymacell. . . . The mere fact that stomata open in the absence of CO2 shows conclusively that the movement is not directly connected with photosynthetic activity, even if the process takes place normally in the...
Pagina 65 - ... dark. Occasionally there is apparent a rhythm corresponding to the daily periodicity, but on the other hand it not unfrequently happens that there may be an irregular decline from the start or the curve may be characterized by a rise or fall without reference to the period of the day. I have noticed on several occasions that pronounced maxima may be found early in the morning — between 5 and 9 o'clock. Manifestly little importance is to be attached to the results obtained under such conditions...
Pagina 137 - By this means it has been found that the rate of transpiration may undergo sudden and wide changes without the accompaniment of a sufficient change in the dimensions of the stomata to account for them on the theory of stomatal regulation of transpiration.
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