FATS. 



71 



OLEAGINOUS PBINCIPLES OP HUMAN 

 FAT. Steariiie and Palmitine crystallized ; Ole- 

 ine fluid. 



death, as the body cools, the Fig. 9. 



stearine and pafmitine some- 

 times separate in a crystalline 

 form, since the oleine can no 

 longer hold in solution so large 

 a quantity as it had dissolved at 

 a higher temperature. (Fig. 9.) 



When in a fluid state, the fatty 

 substances present themselves in 

 the form of drops or globules, 

 which vary greatly in size, but 

 which may be readily recog- 

 nized by their optical proper- 

 ties. They are circular in shape, 

 with a sharp well-defined out- 

 line. They often have a faint 

 amber color, which is distinctly 

 marked in the larger globules, 

 less so in the smaller. As they 



have a higher refractive power than the watery fluids in which they are 

 immersed, they act under the microscope as double convex lenses, and 

 concentrate the light transmitted through them, at a point above the 

 level of the liquid. Consequently, they present the appearance of a 

 bright centre surrounded by a dark border. If the lens of the micro- 

 scope be lifted farther away, the centre of the globule becomes brighter, 

 and its borders darker. These characters will usually be sufficient to 

 distinguish them from other fluid globules of less refractive power. 



The oleaginous matters present a striking peculiarity in regard to the 

 form under which they occur in the living body, and one which distin- 

 guishes them from other ingredients of the animal solids and fluids. 

 The remaining proximate principles of different groups are intimately 

 associated together by molecular union, so as to form either clear solu- 

 tions or homogeneous solids. Thus the saccharine matters of the blood 

 or the milk are in solution in water, in company with the albumen, the 

 lime phosphate, sodium chloride, and the like ; all of them equally dis- 

 tributed throughout the general mass of the fluid. In the bones and 

 cartilages, the animal matters and the calcareous salts are in similarly 

 intimate union with each other ; and in every other part of the body the 

 animal and inorganic ingredients are united in a similar way. But it is 

 different with the fats. For, while the three principal varieties of 

 oleaginous matter are united with each other, they are not united, as a 

 general rule, with proximate principles of other kinds ; that is, with 

 water, saline substances, sugar, or albumen. The fats are soluble to a 

 certain extent in the ingredients of the bile, and they are found in small 

 quantity, in the saponified condition, in the plasma of the blood, as 

 sodium stearate, palmitate, or oleate. But in by far the larger propor- 



