This is a specialized and uncommon microscope. It is signed on the tube E. Leitz, Wetzlar, No. 123111. On the basis of the serial number, it can dated to 1909. It is an example of an entomologist's field microscope. The storage case serves as the base of the microscope. The microscope focuses by rack and pinion. In use, the insect specimen is pinned to a cork which is held in a nickel plated holder attached to an articulated arm. The height and orientation of the specimen can be varied at will. Also attached to another adjustable articulated arm is a bulls-eye condenser that allows the specimen to be illuminated from above. In addition, the microscope is supplied with a mirror allowing observation of the more transparent parts of the specimen (such as the wings). The microscope can be quickly dissembled for storage in the case.

The following was extracted from the 1913 Leitz catalog:

See this translatiion:

The entomological microscope can be dismantled into individual parts and can therefore be conveniently accommodated in a flat, easily portable mahogany case, which also serves as a base for the microscope when it is in use. The microscope is only provided with rack and pinion adjustment, Since only weaker magnifications are possible for enlomological examinations, instead of the usual object table, a removable bracket is attached to the microscope, which has a ball arm on one leg that is easily adjustable; a round piece of cork is attached. The beetles and insects to be examined are placed on this piece. It therefore serves as an object table. To illuminate the objects from above, there is also an articulated arm on the second leg of the bracket, which carries an illumination lens that can be rotated in all directions when it is in use.