NUTRIENT MEDIA AND METHODS OF CULTIVATION. 



123 



Warm Stages. — To apply warmth while a preparation is under 

 continuovis observation, we must either place the microscope Vjodily 



Fig. 50. — Wakm Stage. 



within a special incubator, with the eye-piece protruding through an 

 opening, or we must employ some means of applying heat directly 

 to the prepai-ation. 



A simple warm stage may V)e made of an oblong copper plate, 



Fig. .51.— Warm Stage showx in Opekation. 



two inches long by one inch wide, from one side of which a rod of 

 the same material projects. The plate has a round aperture in the 



