Animal physiology, the structure and functions of the human body / [John Cleland].

  • Cleland, John, 1835-1925
Date:
[1874]
Catalogue details

Licence: Public Domain Mark

Credit: Animal physiology, the structure and functions of the human body / [John Cleland]. Source: Wellcome Collection.

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    ORGANIC MATTER. structures principally implicated in the physiological pro- cesses to be explained; and, in particular, it will be necessary to describe the textures or tissues of the different parts, which in great measure require the aid of the microscope for their examination. This is the department of anatomy termed Histology. 2. Living bodies are termed Organisms, because they are composed of organs, or parts devoted to different purposes ; and the purpose to which any organ is devoted is called its function. Organs are of various degrees of complexity. In organisms of the higher or more complicated description, bodies com- parable with organisms of a- very simple or rudimentary kind exist as textural elements. Such textural elements enter into the formation of more complex textural organs (e.g., arteries in animals, and vascular bundles in plants), which are dis- tributed as component parts of a variety of special organs, such as eye, ear, liver, brain, etc., often the only parts alluded to when the term special organ is used. 3. All organisms are in great part composed, particularly their more active portions, of chemical combinations of a complex kind, called organic matter, together with which there are always, in addition, various mineral constituents and water entering into their composition. The most dis- tinctive character of organic matter is that it is combustible, becoming black when heated over a flame ; and, as this blackness is due to carbon, it disappears on further exposure to heat and air, leaving the ash or non-volatile mineral constituents which are always associated with organic matter. Organic matter is divisible into two groups of substances, which are distinguished as nitrogenous, and non-nitrogenous or carbonaceous; the first containing carbon, hydrogen, oxygen, and nitrogen, and the second having no nitrogen in their constitution. The products of the complete combustion of carbonaceous matters are carbonic acid and water, while nitrogenous substances yield ammonia in addition. The attraction of both carbon and hydrogen for oxygen is very great. Carbonic acid, consisting of one equivalent or combining proportion of carbon and two of oxygen, is the compound which is formed when carbon is freely exposed to