Billy Parr, age 11, of Tucson, Arizona, for his question:

 Can an earthworm grow a new head?

A lizard can grow a new tail, and so can a salamander. A starfish can grow a new arm or even five new arms. But the earthworm can do oven butter. He can grow a new head. In fact, if sliced in half, he may regrow into two separate wormsy etch going his own way. However, not every sliced worm becomes two worms. For this miracle to happen, he must be cut in the right place.

Let's study the earthworms's body before we operate. Mr. Pinky is an annelid animal, a member of the phylum rinnelida, the ringed‑ones. His rings are the segments which girdle his body from tip to tip. They are garters of firm skin alternating with garters of soft, elastic skin. They work together like a concertina and because of them, Mr. Pinky can shorten his body or stretch it out long.

For the operation to be a success, we must count the segments, beginning with true head end.. The hood and of tno tubular worm Is pointed and the tail end is slightly flat. If you are not certain which is the head, wait for the patient to start traveling. Like everybody else, he follows his nose.

Now, from the nose, count beck 18 segments. Select any segment between the 5th end 18th segments. Cut, and your little pink worm is now in two parts. To a higher, more complex animal, this operation is sure to be fatal. But the little annelid will survive.

The front half of the worm will soon begin to grow a new tail. The cut surface seals itself with a small tail segment. Other segments are squeezed in later between the tip and the rest of the body. Five or more new segments may be added in this way. But if the worm lost a grout many segments not all of them will be replaced.

The tail half of the worm will begin to grow a new head. However, no matter how many segments were lost, only five will be replaced. The earthworm is able to grow f~.vc new segments to replace his lost head and this seems to be enough. The operation was a success and one worm has become two worms. One has a new tail, the other has a new head.

But suppose you were a clumsy surgeon and sliced your patient behind his 18th segment. He is cut in two, but his tail half is not very largo, The head end is in splendid condition and soon sprouts a new tail. So all is not lost for we still have one whole worm.

The short tail end puts up a good fight but it is doomed to failure. It starts to regrow now segments but for some reason it cannot regrow new head segments. It grows another tail. 'What we have now is a worm with a tail at each end and no head. The poor creature cannot eat and soon wastes away for lack of nourishment. A worm can grow a new head on the cut tail section. But he can only do this if a fair amount of tail section is left. Growing a new tail seems to be easy, because no matter where ho is cut, the head section will grow a new tail. Growing a new head is harder, though it can be done.