The nervous system is the great inciter of nutrition: when it is vigorous or excited, the digestion is active, the breathing rapid, and the temperature high; and the loss of weight and the possible duration of abstinence follow the same rule.
Man is subject to the same conditions in case of fasting or starvation as warm-blooded animals; and the influences of size, age, and nervous constitution are similar upon him. This is illustrated, in respect to age, in the legend of the family of Ugolin, in which the youngest child died first, at eight years of age, and the other children followed, while the father did not die till three or four days after the death of the last of them. So, in the wreck of the Medusa, the children died first on the raft, the old men next, and the adults last. We might have supposed that the old men would have resisted better; but while they may, perhaps, bear moderate fasting with less inconvenience than more active persons, they are less able to endure starvation. New-born infants are less capable of resistance than adults; but the young of animals—puppies and kittens—are more hardy than we would be ready to suppose. Experiments on new-born children have shown that they can offer considerable resistance to external influences, provided they are well fed. Their mortality is principally due to a deficiency of alimentation called athrepsy, infants dying of which present the same lesions as starved animals. Their fat is exhausted, while the weight of their nervous system is not reduced. Another feature of the starvation of infants is a relative increase in the globules of the blood by dehydration; not that the number of globules is greater, but the proportion of them to the whole volume, a considerable portion of the water having disappeared.
The duration of the possible fast is considerably influenced by fever. That is supposed to determine the production of poisons which stimulate the nervous system and intensify the process of denutrition; so that under its influence, as has been observed in experiments on animals and in man, the weight diminishes more rapidly than under starvation alone.
The influence of drinking is also noticeable. Of two dogs observed by M. Laborde, one died in twenty days; the other, which could drink at will, was still living at the end of thirty-seven days. There are also examples on the other side. Falck's dog went sixty-one days without drinking or eating. Starving dogs usually drink but little, as if warned by instinct not to drink more than they have to. Water, in fact, expedites the wasting of the tissues and accelerates the drain of the salts in the organism. Hence, by drinking, we excrete more chloride of sodium, phosphates, urea, etc., so that, although in general animals deprived of water do not live as long as those which can drink, there is
