Arthur M. Iacurci, age 15, of Trumbull, Connecticut, for his question:

Why does a deer have five stomachs?

Each animal has the built in equipment needed for survival in its proper environment. Teeth, stomachs and other biological details have been suitably perfected through count¬less generations.. An animal without the means to cope with his normal everyday problems simply does not survive long enough to reproduce himself. The deer and their ancestors required highly specialized stomachs to cope with certain everyday hazards in their natural environment.

The handsome members of the deer family are strict vegetarians. Plant food is not easy to digest and some items on the menu are extra tough. Peat is easier to digest and carnivores have simple, fast working digestive systems. Herbivores need larger and more complicated digestive systems. When it comes to dining and digestion, deer must also cope with other problems. They eat no meat themselves, but they provide meat for an assortment of prowling pouncing carnivores. The grass, leafy boughs and other items on their menus are out in risky territory. It is necessary to grab a few bites and run for cover.

During the sunlight hours, the deer are very skillful at hiding themselves in thickets and dappled woodland shade. As a rule, they venture forth to dine at dusk and early dawn. There is not much time for grabbing a bite to eat, but their digestive systems are built to cope with the situation. Their special feeding equipment begins with the teeth. Herbivores need no flesh tearing fangs. Deer have no upper incisor teeth and some have no canines. The lordly wapiti is minus upper incisors and lower canines. The vacant gum spaces are hard and rubbery, just right for gripping, a tuft of greenery.

Each grab of food is hastily swallowed without chewing. It goes down into the rumen, the first of the stomach's separate compartments. 1dhen the rumen is comfortably full, the deer retires to some shady shelter. There he can take his time finishing his meal. The rumen stores the unchewed food and moistens it with digestive juices. With a slight hiccup, the deer brings a bit of this food back into his mouth. There, with his 32 molars and premolars, he patiently chews it. He is chewing the cud. Then he reswallows it and it passes on its way for further processing in the reticulum, the omasum and lastly to the abomasum. Each compartment performs a slightly different func¬tion to break down plant food into nutrients that the deer's body can absorb and use.

Rumen and reticulum, omasum and abomasum add up to four sections in the deer's stomach. Some people call the omasum the psalterium and perhaps this caused some confusion, but the stomach of the deer has only four parts.

A deer may grab his meal in 20 minutes or less. Later he may spend leisurely hours chewing his cud, mouthful by mouthful. Soft grassy foods can be passed through the entire digestive route in 24 hours. Tougher vegetation takes longer. Herbivores that dine on twigs, bark and sturdy roots often require a whole week to send a meal through the works.