DIETETIC DISEASES. 447 



deficiency may relate both to quantity and quality. " A defi- 

 ciency of food," says Dr. Letlieby, " especially of the nitrogenous 

 part, quickly leads to the breaking up of the animal frame. 

 Plague, pestilence, and famine are associated with each other in 

 the public mind, and the records of every country show how closely 

 they are related." It is stated that in cases of very gradual 

 starvation an urgent feeling of hunger is not a prominent symp- 

 tom, and even when it exists at first, it usually soon diminishes, 

 and is succeeded by a feeling of exhaustion and faintness, and 

 even a loathing of food, if abstinence has been long protracted. 

 — (R. B. Holland.) 



Whilst it is essential to health that food should be sufficient, 

 but not over-abundant in quantity, and that its quality should 

 be so regulated as to supply all the wants of the economy, it 

 must be confessed that the lower animals will live for a very 

 long period on very common fare, provided it be sufficient in 

 quantity, and they are not exposed to extreme cold ; but to have 

 health, energy, and condition, both food and water must be good 

 in quality. 



A dietetic disease may be defined to be a morbid condition of 

 the body, brought about by food or water deteriorated in quality, 

 insufficient or over-abundant in quantity, or containing some 

 ingredient directly poisonous or injurious to the animal economy. 



