ii SENSIBILITY OF THE INTEKNAL ORGANS 75 



afferent fibres of the sympathetic are less excitable to hunger- 

 impulses, and only become active some time after the vagi have 

 been cut, or when on prolonged fasting hunger becomes more 

 acute. 



The centres for hunger and thirst are certainly, even if not 

 exclusively, localised in the bulb and pons. This is proved by 

 anencephalous human monsters, which, though they have no 

 cerebrum or cerebellum, utter cries a few hours after birth, make 

 restless movements like normal new-born infants, and like the 

 latter are only stilled when their mouth finds the nipple, which 

 they suck with the same avidity. The renowned " brainless dog " 

 of Goltz also appeared to have sensations of hunger and thirst. 

 At the usual hours for meals its movements were accelerated ; it 

 uttered impatient cries, raised itself and put its fore-paws on the 

 bars of the cage. When a dish of milk and big pieces of meat 

 were brought near its nose it lapped and chewed and swallowed 

 with evident satisfaction, like a normal dog. 



Schiff opposed to the theory of local peripheral origin of 

 hunger and thirst the theory of their central origin. Starting 

 from the fact that abstinence from food and drink alters the con- 

 stitution of the blood, he held that this must directly excite the 

 nervous centres. Local sensations of hunger and thirst are, he 

 says, illusory effects of the state of the centres, according to the 

 general law of the peripheral projection of sensation. Just as the 

 patient has sensations of the amputated limb, so the hungering 

 and thirsting subject feels in the stomach and throat the sensa- 

 tions which really arise centrally. 



This hypothesis is fairly met by the fact that hunger can be 

 diminished even by the introduction of non -nutritive matters into 

 the stomach. In times of famine stones, chalk, and indigestible 

 vegetable remains are often eaten. Thirst can be temporarily 

 relieved e.g. in cases of atresia of the oesophagus, by taking a 

 little water into the mouth. Do not these facts prove that such 

 sensations have a local peripheral origin ? Even more than these 

 exceptional facts, which are difficult of control, we have at hand, 

 within the reach of every one to verify, a valid argument against 

 Schiff's theory viz. that the sensation of hunger Disappears 

 rapidly on introducing food into the stomach long before it has 

 been digested and absorbed, and therefore before the alteration 

 in the blood, which Schiff held to be the direct stimulus to the 

 centres, can have been corrected. The same may be said of the 

 introduction of beverages and the sensation of thirst, the more so 

 since we know how difficult and slow a process is the absorption 

 of water in the stomach. 



To give any experimental basis to Schiff's theory, it would be 

 necessary to prove that the nerve-centres were more excitable to 

 stimuli than the peripheral nerve-endings. Any such attempt, 



