For drawing from the microscope the improved form of the _camera lucida_, or the latest model of the _Edinger drawing-apparatus_ are recommended. Both of these instruments have recently been greatly improved. The _Zeiss microphotographic apparatus_ is by far the best for microphotographic work. For the _polarization-microscope_, _microspectroscope_, and the complicated and expensive _ultra-violet_ and _dark-field_ apparatus the worker is referred to the Zeiss catalogues. A simple and practical _dark-field_ method for the illumination of bacteria, spirochætes and ultramicroscopic particles suspended in fluids requires only a strong illumination and the use of a _Zeiss_, _Leitz_, or _Reichert dark-field condenser_; or the very simple “India-ink” method may be used for the demonstration of spirochætes. (See Staining of Spirochætes.) Especial instruments for easily finding a certain field are obtainable, and are of great convenience in marking slides for photographic purposes. [Illustration: FIG. 51.—A good practical microtome for paraffin and celloidin work. Well-adapted to needs of students and beginners.] Next to the microscope the most important instrument in pathologic work is the =microtome=. One that can be used for either celloidin or paraffin work, and that can also be utilized as a freezing microtome, should be selected in private work, when economy is desired. The majority can be used for either paraffin or celloidin, and one of the Becker models can be easily attached to the carbonic acid holder for the cutting of frozen material. The Bardeen freezing microtome is relatively inexpensive, very satisfactory, and can be easily attached to the carbonic acid tanks. It can be recommended for freezing work. The “slide” type, either that in which the knife-holder is moved by the hand directly or by a crank turned by the hand, is advised for ordinary diagnostic work. For students and beginners the crank is of great advantage, as the knife is securely held and cannot jump. The best microtomes are made by Schanze of Leipzig, Jung of Heidelberg, Becker of Göttingen, the Cambridge Scientific Co., the International Instrument Co., and the Bausch & Lomb Co. For either celloidin or paraffin work the medium or large Schanze slide-microtome or the Minot’s precision microtome are recommended; for cutting serial sections in paraffin the latest modification of the Minot automatic rotary microtome is especially adapted. The best =microtome knives= are made by Walb of Heidelberg. A long, heavy knife is to be preferred to a light one. For the freezing microtome a knife of the type of the blade of a carpenter’s plane set in a wooden handle should be used, Hones and strops of the best quality are necessary.