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c. 1931

SIGNED: Ernst Leitz, Wetzlar



Please Click On Any Picture for a Larger Version


The microscope is a highly modified type. The foot is rectangular and made of a nonmetallic material, possibly hard rubber. A pair of curved supports in a crinkled black finish arise from the foot to join at the top with the pinion box and handle. There is coarse focus by diagonal rack and pinion; fine focus is via a lever on the nosepiece. The included eyepiece is labelled 'Ernst Leitz, Wetzlar, 8X'. The Unusual cone-shaped objective is signed 'Ernst Leitz Wetzlar K 8x'.

The illuminator is supported by buttresses from the bottom which attach to the nosepiece, and two in the middle which attach to the upper midportion of the body tube. The light socket is made of ceramic and sits in a centerable fitting with a three point centering mechanism, on point being sprung, the other two being knobs, similar to a modern condenser centering mechanism used to this day. The illuminator has multiple optical elements and a window on the bottom accepts the filter holder, which in turn can accept different colored filters. Yellow and blue-green filters (latter broken) were enclosed with this instrument when it came to me. The entire illuminator assembly moves with the optical tube as it is focused.

Perhaps the most unusual feature of the microscope is the stage. This is designed to hold and manipulate a human finger. There are two rounded jaws, one each to the right and left side with a tightening screw attached to one side so as to fit to different sized fingers. The entire assembly can be coarsely adjusted by loosening the angled bar. There is a tilting height adjustment which allows viewing from different angles to compensate for the curvature of the finger as it approaches the base of the fingernail.

The original leather-covered case is lined with purple velour, and has fittings to accept the stage assembly, glass filters, and eyepieces. The electric cord is attached to a standard 110 volt plug. The original cord is fraying and the original bulb is lacking.


The idea of studying capillaries under the microscope dates back many centuries. In 1628 William Harvey described the circulation of blood, and the heart as its pump. Harvey did not visualize the capillaries, instead referring to 'pores.' It was not until 1661 that Marcello Malpighi first visualized, via a microscope, the movement of red blood cells through capillaries of the lung and the urinary bladder of a frog. In 1663 Johan Kolhaus was apparently the first to visualize the capillaries of the nail fold. The use of oil to make the skin over the capillaries in this area more transparent was apparently first suggested by Unna in 1893.
Starting about 1916, Professor Otfried Muller of Tubingen, Germany studied many types of capillaries including those of the nail fold; this culminated in his magnificent 1922 book and color atlas 'Capillaries of the Surface of the Human Body in Health and Disease.' Zeiss credited him with the design of the smaller and simpler Muller microscope shown elsewhere on this website here. Other manufacturers made nailfold capillary microscopes; Bausch and Lomb marketed one for this purpose about 1929. From the early 1920's until at least 1934, Muller's Skin Microscope was featured in their catalogs.

Today the technique of capillary microscopy is occasionally used to help diagnose rheumatic diseases, especially scleroderma and other connective tissue diseases. The normal capillaries of the skin at the base of the nail are relatively uniform in thickness and often (but not always) relatively straight curved loops resembling the closed end of a 'bobby pin'; in these diseases however they become deformed both in course and diameter and there may also be associated tiny hemorrhages or avascular areas lacking capillaries completely. These features are only visible with magnification greater than that provided by, for example, a magnifying glass. An ordinary microscope could be used for this purpose with top-side illumination, but having the subject's finger hold steady on a stage without support for his or her arm, would be very difficult. This is the main advantage of this kind of microscope, as the special stage in the foot plate keeps the finger centered, and the subject's arm can rest on the table. It has been said that tortuosity of the vessels can also reflect these conditions, but as seen in the illustration here, from a normal male subject (the author!), tortuous nail fold capillaries can be found in normal persons, especially males. A recent form of nailfold capillary microscope with integral digital camera, also has a mechanical stage which gently grips the finger.