PUPAL SLEEP

The pupal stage of insects which undergo metamorphosis, is that immediately following the larval stage. The term chrysalis has almost the same value as pupa. If the insect is not wholly quiescent during this pupal stage the word nymph is used. Since the larval stage of most insects differs so markedly from the adult stage, the pupal stage constitutes the intermediate stage in which the necessary bodily changes are effected. It is a period of internal transformation, during which most pupa are outwardly quiescent, they move very little, and do not eat at all. The marvellous structural and functional transformations take place during this period of abstinence from food, the pupa depending entirely upon its stored reserves for the accomplishment of its structural revolution. Pupal sleep may be artificially prolonged.

FASTING AFTER BIRTH

Fasts of longer or shorter durations are seen in many animals immediately after birth. For example, Fabre tells us that certain spiders eat no food for the first six months of their lives, but feast upon sunbeams. Chickens take neither food nor water for the first three days after they hatch from the egg. In most mammals there is no milk secreted for three or more days after their young are born. The fluid, secreted during this period is devoid of food value.

FASTING WHEN NOT HUNGRY

Many animals normally go for long periods between feedings, not eating for the reason that they are not hungry. For example, there are many snakes that eat only at long intervals.

FASTING WHEN ANGRY OR EXCITED

An animal will refuse food when angry or excited. Indeed, an animal that is hungry and in the process of eating may be angered and will cease eating. Angry animals do not resume eating again until their anger has subsided. Reports of dogs grieving over the absence or death of their owners, refusing food for long periods, are often carried by the press.

FASTING IN CAPTIVITY

Some animals refuse to eat when held in captivity. They will starve to death rather than live as captives thus making good Patrick Henry's ringing cry: "Give me liberty or give me death." One of these is the famous marine iguana, Amblyrhymchus Cristatus, a seashore lizard, of the Galapagos Islands, described as the "Vegetarian dragon" and "Fasting man." The Iguana feeds on sea-weeds and can abstain from food for long periods--over a hundred days.

EXPERIMENTAL FASTS

Many thousands of animals of all kinds have been employed in experimental fasts. Insects, fishes, snakes, birds, rodents, rabbits, badgers, cows, horses, and many other types of animals have been used in fasts of varying lengths of time. In many of these fasts, the period of abstinence from food has been extended far beyond the normal limit of the fast into the period of starvation, some of them being ended before death occurred, others being carried on to death. While we are opposed to the suffering caused in animals by pushing the period of abstinence beyond the return of hunger, it has been done and the information thus obtained is available, and we are at liberty to make use of it in our studies of the subject. Many of these experimental fasts will be referred to as we proceed in our study.

Date: 2015-01-11; view: 799