122 PHYSIOLOGY FOR DENTAL STUDENTS. 



most alarming symptoms of neuritis (paralysis, weakness, etc.), 

 which however disappear in a few hours, not only when unpol- 

 ished rice or rice polishings (or husks) are given, but also when 

 meat, or beans, or a small piece of yeast is mixed with the rice. 

 Attempts have naturally been made to isolate the substance 

 which is responsible for this remarkable action, and indeed some 

 success can already be reported. For example, it has been pos- 

 sible to separate from rice polishings and from yeast small traces 

 of crystalline substances having a most powerful action in pre- 

 venting neuritis. 



Even such success in investigating the cause of Beri-Beri in 

 rice-feeders would scarcely warrant us in asserting that vita- 

 mines are essential constituents of our own varied diets. To show 

 that they are, however, has been no very difficult task. Thus, it 

 is known that although young rats thrive admirably. on milk diet, 

 they fail to do so on one of artificial milk, that is, of milk made 

 in the laboratory by mixing together, in proper proportions, the 

 same proteins, fats, carbohydrates and salts that occur in milk. 

 In this chemical mixture, something is wanting which exists only 

 when the ingredients of milk are compounded by the mammary 

 glands. The addition to synthetic milk of desiccated milk from 

 which most of the proteins had been removed bestowed on it full 

 nutritive value. 



The practical importance of this observation in the feeding of 

 infants, we need not insist on. Suffice it to say that it is quite 

 possible that prolonged boiling of milk, as for its sterilization, 

 may deprive it of vitamines and thus render the child liable to 

 such diseases as rickets and infantile scurvy, or at least interfere 

 materially with its proper development and growth. Among the 

 symptoms thus produced, especially in the case of infantile 

 scurvy, ulcers may develop on the gums, or the teeth may become 

 loosened. Change of diet may in a few days restore perfect 

 health, or even the addition of a few teaspoonfuls of orange or 

 lemon juice to the original diet may suffice. It is often miracu- 

 lous how quickly such treatment may change a fretful, pain- 

 stricken child to one of perfect health and cheerfulness. 



Innumerable other examples of the wonderful influence of 



