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action active alimentary canal animals appears archenteron arrangement bacteria become Biology blood body branches called carbon cavity cells changes chemical closely complex composed consists contains continually course covered cytoplasm differentiation digestion direction divided division dorsal earth earthworm energy environment essentially extending fact fern finally fluid follows function fundamental give growing higher important individual kind known later layer leaf leaves less lifeless matter living matter living things mass membrane microscope mouth movements muscles nature nearly nerves nucleus opening organs original outer oxygen pass physiological plants portion probably produced properties proteids protoplasm Pteris reproduction rhizoids rhizome seen separated showing shown side similar single skin somite species spores stages starch structure substance surface takes tion tissues tube usually various vegetal ventral vessel walls waste whole worm young
Page 34 - C.) produce also the death of most organisms. "Amongst the organic proximate principles which enter into the composition of the tissues and organs of living beings, those belonging to the class of proteid or albuminous bodies occupy quite a peculiar place and require an exceptional treatment, for they alone are never absent from the active living cells which we recognize as the primordial structures of animal and vegetable organisms. In the plant, whilst we recognize the wide distribution of such...
Page 4 - The increase of size which constitutes growth is the result of a process of molecular inter-susception, and therefore differs altogether from the process of growth by accretion.
Page iii - We have sought to lead beginners in biology from familiar facts to a better knowledge of how living things are built and how they act, such as may rightly take place in general education, or may afford a basis for further studies in general biology, zoology, botany, physiology, or medicine.
Page 2 - ... expelled in new combinations. " The parallel between a whirlpool in a stream and a living being, which has often been drawn, is as just as it is striking. The whirlpool is permanent, but the particles of water which constitute it are incessantly changing. Those which enter it on the one side are whirled around and temporarily constitute a part of its individuality; as they leave it on the other side, their places are made good by new comers.
Page 2 - ... a stationary hillock of water. Viewed closely, it is a typical expression of the conflicting impulses generated by a swift rush of material particles. Now, with all our appliances, we cannot get within a good many miles, so to speak, of the crayfish. If we could, we should see that it was nothing but the constant form of a similar turmoil of material molecules which are constantly flowing into the animal on the one side, and streaming out on the other.
Page 221 - ... light, filter, and add 25 cc of glycerine and 25 cc of methyl alcohol.
Page 4 - But the increase of size which constitutes growth is the result of a process of molecular intus-susception, and therefore differs altogether from the process of growth by accretion, which may be observed in crystals and is effected purely by the external addition of new matter — so that, in the well-known aphorism of Linnaeus,* the word " grow," as applied to stones, signifies a totally different process from what is called " growth