58 MANUAL OF PHYSIOLOGY. 



from protoplasm carbohydrates represented by glycogen, lecithin, 

 and other fats, and several albuminous bodies, which will be de- 

 scribed in the groups to which they belong. In addition to these, 

 protoplasm often contains some foreign bodies which have come 

 from without, and special ingredients of its own manufacture, such 

 as oil, pigment, starch, and chlorophyll. 



Blood-plasma: There is another body in living blood which 

 must be included in this group, as it undoubtedly has a much 

 more complex constitution than any of the individual albuminous 

 bodies, presently to be described, which can be obtained from it. 

 This is proved by the following facts: first, its death is accompa- 

 nied by a series of chemical changes, viz., disappearance of free 

 oxygen, diminution of alkalinity, and a rise in temperature, and 

 secondly, that several albuminous bodies appear which were not 

 present as such, in the living plasma. 



The spontaneous decomposition of separated blood- plasma may 

 be delayed by cold ; at freezing point the chemical processes are 

 thus held in check. During life the exalted constitution of the 

 plasma is sustained by certain chemical interchanges which go on 

 between it and its surroundings. This question will be more fully 

 discussed when the coagulation of the blood is described. 



Muscle-plasma: Likewise, as will be found in the chapter on 

 Muscles, there exists in the soft, contractile part of striated mus- 

 cles a plasma which at its death spontaneously breaks up into 

 several distinct albuminous bodies and forms a coagulum. These 

 changes are accompanied by acidity of reaction, the disappearance 

 of oxygen and an elevation of temperature, showing that distinct 

 chemical change is taking place. 



Oxy-hwmoylobin, the coloring matter of the blood, should be 

 included here amongst the important chemical bodies more com- 

 plex than the albumins. This singular body can be broken up 

 into a globulin and a coloring matter hce-mntin containing iron. 

 It differs from all other bodies of a similarly complex nature from 

 the fact that it readily crystallizes, and also in the very remark- 

 able manner in which it combines with oxygen, and again yields 

 it up. 



