The ultrastructure of the “Podura” scale ( Lepidocyrtus curvicollis, insecta, collembola), as revealed by whole mounts

The markings on the scales of Lepidocyrtus curvicollis were a standard test object for light microscopy over a period of a century, and they played an important part in the development of the achromatic objective; but they were too minute for resolution of the true structure. The electron microscope reveals that each mark is an excessively narrow spine, freely projecting at one end, but attached to the surface of the scale over the greater part of its length.