HUNGER AND APPETITE 



475 



period include an increase in the pulse rate and vasodilatation. By 

 comparing plethysmographic tracings of the arm volume (see page 230) 

 and stomach contractions, it has been found that the increase in volume 

 occurs pari passu with the increasing tonus of the stomach, but that it 

 begins to shrink before the stomach contraction has reached its maximum. 

 Occasionally, however, as in acute hunger, a somewhat different rela- 

 tionship obtains, vasoconstriction being more prominent. During each 

 hunger contraction there is also increased salivation, the degree of 

 which varies with different individuals. This salivation is independent 

 of the more copious "watering of the mouth" that accompanies the 

 thought or sight of appetizing food. 



j L 



tttttttttttttttttWtttttttttlttr' 



-ttttttttttttttttttmttttttttttttttfitmtttitttnitittni 



Fig. 169. Showing augmentation of the knee-jerk (upper tracing) during the marked hunger con- 

 tractions (lower tracing). (From Carlson.) 



HUNGER DURING STARVATION 



During enforced starvation for long periods of time, it is known 

 that healthy individuals at first experience intense sensations of hunger 

 and appetite, which last however only for a few days, then become less 

 pronounced and finally almost disappear. It is of interest to know the 

 relationship between these sensations and the hunger contractions in 

 the stomach. This has been investigated by Carlson and Luckhardt, who 

 voluntarily subjected themselves to complete starvation, except for the 

 taking of water, for four days. During a great part of this time records 

 of the stomach contractions were taken by the balloon method, and it 

 was found that the tonus of the stomach and also the frequency and 

 intensity of the hunger contractions became progressively more pronounced 

 as starvation proceeded. Towards the end of the period it was also noted 

 that incomplete hunger tetanus made its appearance where ordinarily, 

 as in Carlson's case, this type of hunger contraction was infrequent. 

 Sensations of hunger were present more or less throughout the period, 

 being therefore probably due to the persistently increased tonus. The 

 onset of a period of hunger contraction could usually be foretold by an 



