EXAMINATION OF ANIMAL FLUIDS. 



683 



FiQ. 396. 



microscopic changes -whicli the blood undergoes in. plethora, fever, 

 and various other diseases, have yet to be accurately determined. 



Milk. — A microscopic exa- 

 mination of milk reveals a 

 number of spherical bodies, 

 having dark, smooth, and vrell- 

 defined margins, and a trans- 

 parent and highly refractive 

 centre, and varying from a 

 mere point up to the l-4000th 

 or l-3000th of an inch in dia- 

 meter. These bodies consist 

 of oil-globules invested with a 

 covering of albumen, which 

 prevents them from running 

 together and forming larger 

 globules when pressed between 

 two pieces of glass. If this 

 albuminous membrane be dis- 

 solved with a little acetic acid 



or carbonate of soda, the oil is separated, and may be readily 

 collected. Under this treatment the smaller globules may be 

 made, by the slightest pressure, to run together and form larger 

 ones. These globules collecting on the surface of milk, in virtue 

 of their lighter specific gravity, constitute cream. An excess 

 of ether effects the solution of the milk-globules, while water 

 causes them to swell out. 



The colostrum or first milk 

 of the human female is yellow 

 in color, and contains many 

 large cells filled with oil, and 

 mingled with a number of 

 compound granular bodies, 

 which disappear about the fifth 

 or sixth day after delivery. 

 (Fig. 397.) 



In fresh and healthy milk, 

 the globules are more or less 

 uniform in size, and move 

 freely in the surrounding fluid, 

 showing no tendency to aggre- 

 gate in masses. (Fig. 398.) 



The microscope readily de- 

 tects adulterations of milk. 



The addition of water causes the globules to be separated far- 

 ther from each other. The presence of flour is determined by 

 large starch-corpuscles, which strike a blue color with iodine. 

 Gritty particles, soluble in the mineral acids, indicate the addition 



Fig. 397. 





