The Physiology of StomataCarnegie Institution of Washington, 1908 - 142 pagina's |
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Pagina 5
... Leitgeb and verified by Darwin , may be cited as an example . To be sure , the attempt has been made to explain such activity by referring the stoma to the class of irritable mechanisms , but unfor- tunately such treatment is not ...
... Leitgeb and verified by Darwin , may be cited as an example . To be sure , the attempt has been made to explain such activity by referring the stoma to the class of irritable mechanisms , but unfor- tunately such treatment is not ...
Pagina 29
... Leitgeb in the moribund stomata of Galtonia candicans . When , however , the stoma has become widely open it then very suddenly closes , as with a snap , so that unless one is actually observing the effect of the reagent the closed ...
... Leitgeb in the moribund stomata of Galtonia candicans . When , however , the stoma has become widely open it then very suddenly closes , as with a snap , so that unless one is actually observing the effect of the reagent the closed ...
Pagina 30
... Leitgeb by killing with iodine vapor and chloroform , and the opening under these reagents was quite as marked as in my fig . 9 , which shows the forms assumed by stomata on treatment with strong potas- sium hydrate . It would seem ...
... Leitgeb by killing with iodine vapor and chloroform , and the opening under these reagents was quite as marked as in my fig . 9 , which shows the forms assumed by stomata on treatment with strong potas- sium hydrate . It would seem ...
Pagina 88
... ( Leitgeb ) . " Visible wilting " is , however , a purely artificial criterion . The danger - point , which , during wilting , we do not know much about , may be reached and passed before visible wilting is manifest . This phase of the ...
... ( Leitgeb ) . " Visible wilting " is , however , a purely artificial criterion . The danger - point , which , during wilting , we do not know much about , may be reached and passed before visible wilting is manifest . This phase of the ...
Pagina 97
... ( Leitgeb ) , and I have myself found them in Buxus , Agave , lilac , privet ( apparently not noted by Pirotta ) , and in another species of Verbena . * This substance is undoubtedly of quite common occurrence in stomata . In Occurs also ...
... ( Leitgeb ) , and I have myself found them in Buxus , Agave , lilac , privet ( apparently not noted by Pirotta ) , and in another species of Verbena . * This substance is undoubtedly of quite common occurrence in stomata . In Occurs also ...
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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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