34 



in this way have thrust upon them more than their normal 

 task. Partial digestion of food should take place in the 

 stomach and other digestive organs, and completed diges- 

 tion should take place in the intestines. 



EXPERIMENT 23. A NATURAL EMULSION 



Fats are digestible when in the form of emulsion ; hence 

 a food which contains fat in that form is easily digestible 

 and valuable for nutrition. 



(a) Put a drop of milk on a clean piece of glass and 

 examine it under the microscope (Fig. 25). Notice the fat 



FlG. 25. Globules of fat in skim milk, milk, and cream, as seen through the 



microscope. 



globules and the liquid in which they float. What do you 

 suppose the liquid is ? Sketch what you see under the 

 microscope. 



(b) Repeat the examination for skim milk and cream. 

 Which contains the greatest number of fat globules? 



