1 4 PHYSIOLOGY. 



although apparently killed by the drying up of the fluid in which 

 it had been immersed, will speedily renew its active movements on 

 being again supplied with water. 



Organized bodies are capable of being resolved by chemical 

 analysis, into the inorganic simple elements ; but the list of sub- 

 stances obtained from this source, is small in comparison with 

 those found in the inorganic world, being only about seventeen. 

 Of these, four alone, are considered essential, viz., carbon, oxy- 

 gen, hydrogen, and nitrogen. Two, at least, of these will be found 

 in every organic compound. The other simple substances are 

 found in smaller quantities, and are less extensively diffused ; these 

 may be called its incidental, or non-essential elements. These 

 are, sulphur, phosphorus, chlorine, sodium, calcium, potassium, 

 magnesium, silicon, aluminum, iron, manganese, iodine, and bro- 

 mine ; the last two are obtained almost exclusively from marine 

 plants and animals. Between these elementary substances and 

 the organized animal, or vegetable structure, there exists a class 

 of compounds, called proximate principles, or organic compounds, 

 or organizable substances. These are obtained in the first stage 

 of chemical analysis of the various animal and vegetable tis. 

 sues, and may be resolved by further analysis into their simple 

 elements. For example, by the first analysis of muscle, we obtain 

 the proximate j)f'inciple, caWed Jib r in , which is its chief constituent; 

 subsequently, by the analysis of fibrine, we obtain the simple ele- 

 ments, oxygen, hydrogen, carbon, nitrogen, and sulphur, in certain 

 proportions. So, on the other hand, by synthesis, the inorganic 

 elements will produce the organic compound fibrine ; from which 

 again, the organic structure muscle is obtained. This latter, how- 

 ever, has- never been effected in the laboratory, but solely in the living 

 body. 



The true proximate principles are those substances which are first 

 obtained by the analysis of the organized textures ; such are, gluten, 

 starch, and lignine, from the vegetable ; and albumen, caseine, or 

 fibrine, from the animal textures. From these again are derived a 

 great variety of products by various processes, owing to the ten- 

 dency which their elements have to form new combinations. For 

 example: by boiling starch in dilute acids, it becomes converted into 

 a kind of gum, and starch sugar. A large class of organic com- 

 pounds is thus formed, which it seems proper to distinguish from the 

 true proximate principles, under the name of secondary organic 

 compounds. 



In analyzing both the primary and secondary organic ele- 

 ments, they are found, in the majority of cases, to be composed 

 of three or four essential elements ; although in the secondary orga- 

 nic products of the vegetable class, we meet a few instances of 

 binary compounds of simple elements. 



