Class-book of physiology : for the use of schools and families : comprising the structure and functions of the organs of man, illustrated by comparative reference to those of inferior animals . rnicious to animallife, is given off. Thus the two great kingdoms of naturemutually furnish those elements which are essential to thelife of each other. Plants purify the air for the use of an-imals, and maintain in it a supply of that element, withoutwhich animals cannot exist. Animals, in turn, furnish theessential element for the growth of all vegetable struct-ures, by parting with that which is usel
Class-book of physiology : for the use of schools and families : comprising the structure and functions of the organs of man, illustrated by comparative reference to those of inferior animals . rnicious to animallife, is given off. Thus the two great kingdoms of naturemutually furnish those elements which are essential to thelife of each other. Plants purify the air for the use of an-imals, and maintain in it a supply of that element, withoutwhich animals cannot exist. Animals, in turn, furnish theessential element for the growth of all vegetable struct-ures, by parting with that which is useless and evenpoisonous to themselves. 83. In animals, the necessary condition for the functionof respiration is a membrane supplied with the circulating What is respiration 1 What is said of the necessity of respiration in plantsand in animals? How does the process of respiration take place in plants?Of what is carbonic acid composed ? How do plants dispose of the oxygen ? how the carbonic acid 1 How do animals dispose of the oxygen 1—how the carbon 1 How do plants affect the air 1 What is the necessary conditionfor the function of respiration in animals ?4 48 CLASS-BOOK OF fluid on one side, and the air on the other. But the sameprinciple is so modified in the different groups of animalsas to adapt it to their various modes of life. In some, thisis the only condition; in others, there is a complication oforgans, all tending to make this condition more Thus, in the lowest groups, olwhich the hydra is an example {fig. 14),the respiration takes place through thewhole surface of the animal, and iscalled cutaneous respiration. This kindof respiration is found to some extentin all the higher orders of animatedbeings, and is of no inconsiderableimportance even to man. In manyof the cold-blooded animals it isequally important with that performedby the special organs of frog, for example, will live longerwith his mouth and nostrils com-pletely
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectphysiologicalprocess
