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absorbed absorption alcohol amount appears assimilation atmosphere bark become Botanische calcic carbonic acid cell-wall cellulose cent changes chemical chlorophyll chlorophyll granules cirele color coloring-matter containing cork cortex cotyledons crystals cutinized cylinder Darwin dicotyledons dilute dissolved ducts elements embryo epidermis evaporation examined experiments fascicles fibres fibro-vascular bundles film flower germination given glass glycerin grains green growth hairs hydrochloric acid inches instance intereellular iodine layer leaf leaves light liquid lower plants mass matters membrane micellae microscope minute moisture monocotyledons movement nearly nitric acid nitrogen nucleus observed organs ovule oxygen parenchyma petiole Pfeffer plants pollen pollen-grains portion potassic produced protein protoplasm radial radicle rays reagents roots Sachs seedlings seeds shown side soil soluble solution sometimes species specimen stareh stem stoma stomata structure substance surface temperature thickness thin threads tion tissues tracheids transpiration tube vegetable wall wood wood-cells woody yellow young
Page 324 - I first put a sprig of mint into a glass jar standing inverted in a vessel of water; but when it had continued growing there for some months, I found that the air would neither extinguish a candle, nor was it at all inconvenient to a mouse which I put into it.
Page 301 - According to the physical hypothesis now generally received, a gas is represented as consisting of solid and perfectly elastic spherical particles or atoms, which move in all directions, and are animated with different degrees of velocity in different gases.
Page 395 - ... case. . . . The growing part, therefore, does not act like a nail when hammered into a board, but more like a wedge of wood, which, whilst slowly driven into a crevice, continually expands at the same time by the absorption of water ; and a wedge thus acting will split even a mass of rock.
Page 416 - If the tip be lightly pressed, or burnt or cut, it transmits an influence to the upper adjoining part, causing it to bend away from the affected side ; and, what is more surprising, the tip can distinguish between a slightly harder and softer object by which it is simultaneously pressed on opposite sides.
Page 223 - ... activity of their own, arising out of their physical properties. While the rigidity of the crystalline structure shuts out external impressions, the softness of the gelatinous colloid partakes of fluidity, and enables the colloid to become a medium for liquid diffusion, like water itself. The same penetrability appears to take the form of a capacity for cementation in such colloids as can exist at a high temperature.
Page 424 - Finally, it is impossible not to be struck with the resemblance between the foregoing movements of plants and many of the actions performed unconsciously by the lower animals.* With plants an astonishingly small stimulus suffices ; and even with allied plants one may be highly sensitive to the slightest continued pressure, and another highly sensitive to a slight momentary touch. The habit of moving at certain periods is inherited both by plants and animals; and several other points of similitude...
Page 447 - ... to be so from the observation of a series of intermediate forms which bridge over the differences. Only observation can inform us how much difference is compatible with a common origin. The general result of observation is that plants and animals breed true from generation to generation within certain somewhat indeterminate limits of variation ; that those individuals which resemble each other within such limits interbreed freely, while those with wider differences do not. Hence, on the one hand,...
Page 417 - ... it. But as the growing stem lengthens and rises, the tendril might strike against it and be wound up around it. It never does. If we watch these slender Passion-flowers, which show the revolving so well in a sultry day, we may see, with wonder, that when a tendril, sweeping horizontally, comes round so that its base nears the parent stem rising above it, it stops short, rises stiffly upright, moves on in this position until it passes by the stem, then rapidly comes down again to the horizontal...
Page 223 - Although chemically inert in the ordinary sense, colloids possess a compensating activity of their own, arising out of their physical properties. While the rigidity of the crystalline structure shuts out external impressions, the softness of the gelatinous colloid partakes of fluidity, and enables the colloid to become a medium for liquid diffusion, like water itself.
Page 417 - It is hardly an exaggeration to say that the tip of the radicle thus endowed, and having the power of directing the movements of the adjoining parts, acts like the brain of one of the lower animals ; the brain being seated within the anterior end of the body, receiving impressions from the sense-organs, and directing the several movements.