76 ANATOMY. 



114, and stearin at 118 ; whilst olein is fluid at ordinary tempera- 

 tures, but solidifies at 50. 



Oleic, butyric, and probably some other volatile fatty acids, propio- 

 nic and caproic, exist in the milk. 



The so-called glycero- phosphoric acid is found in the brain : it is 

 formed of phosphoric acid and glycerin. The phosphorus of the brain 

 has also been regarded as occurring in combination with oleic acid, as 

 an oleophosphoric acid ; but this is doubtful. 



Cholesterin is a sort of animal resin, which crystallizes in beautiful 

 microscopic white scales. It occurs chiefly in the brain and in the 

 bile, and forms the substance of most gall-stones. It also accumulates 

 in certain morbid fluids and diseased tissues. 



Starch and sugars of different kinds are found in the body. Thus, 

 there is either an amylaceous, sugar-forming or glycogenic substance, 

 named amylin, glycogen, or hepatin (from yluxtx;, glucus, sweet, and 

 yebofjuu, geinomai, to become), or else a kind of sugar, named glucose, 

 dextrose, or grape-sugar, in the liver, and in the blood of the veins 

 which leave that organ. There is another kind of sugar in muscle, 

 called inosite. Lastly, in milk, there is a large quantity of lactin or 

 sugar of milk, which, in solution and in contact with azotized matter 

 or a ferment, easily decomposes, and forms lactic acid, as happens in 

 the souring of milk. 



Lactic acid itself is also found in the blood as a lactate of potash or 

 soda, in muscle, in the perspiration, and in the renal excretion. It 

 is met with also in the gastric juice. 



Formic and acetic acids exist in the perspiration, and sometimes 

 oxalic acid in the urine. 



The above-named saccharine and acid substances are all soluble in 

 both water and alcohol. 



The Chemical Composition of the several Tissues. 



Such being the characters of the principal proximate organic and 

 inorganic constituents of the animal body and its various fluids, it 

 must be understood that these various substances may be extracted 

 from, or shown to exist in, the different tissues, in certain definite 

 quantities; in other words, that they may be obtained separately from 

 each other, by taking advantage of their different behavior when 

 acted on by water, alcohol, or ether, by evaporating their respective 

 solutions in those fluids, and by drying or burning the tissues them- 

 selves. For example, the composition of the white substance of the 

 brain is ascertainable by some such process as the following: 



A given weight, sufficiently large to cover small errors, is first 

 dried, at a temperature of 212, in a water-bath, so as to show, by 

 the loss through evaporation, the quantity of water it contained. The 

 dried mass, cut or broken up, and then acted on by successive portions 

 of ether, will yield to that fluid its fatty matters, which may be ob- 

 tained separately, so as to be weighed, by allowing the ethereal solu- 

 tions drawn off from the undissolved residue to evaporate sponta- 

 neously. Those residual undissolved matters acted on successively by 

 hot alcohol, will yield to that menstruum, besides further traces of 



