Half & Half

At California's Stanford University last week Biologist Dietrich Bodenstein displayed a winged insect which was half immature pupa, half mature butterfly. This monster was a by-product of Dr. Bodenstein's discovery of the agency which causes the final metamorphosis from pupa to adult. It is a growth substance generated in the head which reaches the tissues through the skin. It may be a hormone, but since hormones have not previously been found in insects it may also be an enzyme or some sort of nerve stimulus.

Dr. Bodenstein cut off the circulation of the substance back of the pupa's head.* The head and shoulders metamorphosed normally, the mouth lost its caterpillar jaws and acquired a honey-sucking proboscis, the shoulders sprouted wings. But the body, deprived of the stimulus, remained frozen in the pupal stage.

*The pupae of many butterflies do not wrap themselves in cocoons bu, 'Depend on protective coloration for security, can therefore easily be used for laboratory experiment.

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