Elementary text-book of zoology (1884) Elementary text-book of zoology elementarytextbo0101clau Year: 1884 MOVEMENT AND SENSATION AS TEST OF ANIMALS. 2L of carbonic acid goes on. In plants, therefore, together with the characteristic deoxidation process, there is always found a process of oxidation analogous to that occurring in animal me- tabolism ; by which a part of the assimilated substances is again destroyed. The growth of plants is impossible without the con- sumption of oxygen and the production of carbonic acid. The more energetic the growth, the more oxygen is consumed, as indeed th
Elementary text-book of zoology (1884) Elementary text-book of zoology elementarytextbo0101clau Year: 1884 MOVEMENT AND SENSATION AS TEST OF ANIMALS. 2L of carbonic acid goes on. In plants, therefore, together with the characteristic deoxidation process, there is always found a process of oxidation analogous to that occurring in animal me- tabolism ; by which a part of the assimilated substances is again destroyed. The growth of plants is impossible without the con- sumption of oxygen and the production of carbonic acid. The more energetic the growth, the more oxygen is consumed, as indeed the germinating seed or the quickly unfolding leaf arid flower buds rapidly consume oxygen and excrete carbonic acid. In this con- nection should be mentioned the fact that the movements of proto- plasm depend upon the inspiration of oxygen. The production of heat (in germination), also of light (Agaricus olearius) is accompanied by an active consumption of oxygen. Finally, there are organisms (yeast cells, Schizomycetes) which indeed manufacture both nitro- genous and albuminous compounds, but do not assimilate the carbon of carbonic acid, but rather derive the necessary carbon from pre- pared carbohydrates (Pasteur, Cohn). 5. Voluntary movement and sensation, according to the common view, is the chief characteristic of animal life. Formerly, the power of free locomotion was looked upon as a necessary property of animals; and as a consequence of this the fixed colonies of Polyps were considered to be plants, until Peyssonnel brought forward proof of their animal nature, a view which by the influence of the great naturalists of the last century has gained general recognition. More recently, on the discovery of the existence of motile spores of alga?, it was first recog- nised that plants also, especially at certain stages of their development (fig. 9), possessed the power of free locomotion, so that we are compelled to direct our attention to the signs by which the voluntary „
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