Vital Ingredient

It is man's most precious possession—no living thing can exist without it. But when they gave it to Orville, it killed him. For the answer, read 1/M.
Now watch, Remm said, indicating the native. Macker had been absent, exploring the countryside in the immediate vicinity of their landing place, and had not witnessed the capture of the native, or the tests his two companions made on it.
Macker followed Remm's gaze to where the biped native sat hunched. The creature was bent into an ungainly position, its body crooked at incongruous angles, in such a way as to allow most of its weight to rest on a packing-box at the base of a middle angle. Its stubby feet, on the ends of thin, pipelike legs, rested against the floor of the space ship. Its body was covered, almost entirely, with an artificial skin material of various colors. Some of the colors hurt Macker's eyes. In the few places where the flesh showed through the skin was an unhealthy, pallid white.
Slowly the creature's head swiveled on its short neck until it faced them.
Those orifices in the upper portion of its skull are evidently organs of sight, Remm said. It sees that we are quite a distance away. It will probably attempt to escape again.
Slowly—slowly—the native's head rotated away from them in a half-circle until it faced Toolls, working over his instruments on the far side of the room. Then it turned its head back until it faced the door of the ship.
It is setting itself for flight now, Remm said. Notice the evidence of strain on its face.
The creature leaned forward and the appendages on the ends of its upper limbs clutched the sides of the box as it propelled its body forward.
It raised its right foot in a slow arc, employing a double-jointed, breaking action of its leg. For a long moment it rested its entire weight on its lumpy right foot, while its momentum carried its body sluggishly forward. Then it repeated the motion with its left leg; then again its right. All the while evidencing great exertion and concentration of effort.