SCALE OF PODURA (The springtail, Lepidocyrtus curvicollis):

The scale of podura has been used as a test object since the early 19th century. This scale is from a Test Slide supplied by C.M. Topping. With increasing magnification and numerical aperture the markings take on the appearance of an exclamation mark (without the period at the bottom), and with 100 X, sometimes show a central white area. Electron micrographs have proven that these are actually tiny spines. A dashed appearance on the scales is apparent with brightfield illumination even with a 10X objective. A 40X objective reveals the overall shape of these. Oil immersion is required to show the hollowed out appearance of the spines and I found the best imaging of this with my 100X Apo S-plan oil objective with oiled NIC illumination. I did not find green or blue filters with oblique illumination to improve the imaging.