METHODS. 11 



For low powers, the plane mirror and the large diaphragm are 

 in order, while higher powers require the use of the concave 

 mirror and small diaphragms. All powers of the microscope 

 exceeding 800 diameters are reached to-day by immersion lenses. 

 If an immersion lens be employed, the microscope should be 

 placed at a certain distance from the window, or else kerosene- 

 light be resorted to. For researches with immersion lenses in 

 daylight, the time between eleven and twt) o'clock is the best, 

 though light-condensing lenses placed below the level of the 

 specimen may prove useful at other times of the day. 



As soon as investigation commences, the note-book and the 

 pencil must be on hand, in order to fix every observation on 

 paper, though even in no better shape than that of a rough sketch. 

 Nobody can be a good observer with the microscope unless he is 

 a draughtsman. If the eyes be not educated in seeing, and the 

 hand in reproducing on paper what the eyes perceive, all efforts 

 to gain correct ideas of what the microscope teaches are in vain. 

 To see with the microscope is a difficult art, requiring many 

 years of thorough education. The assistance of a reliable 

 teacher cannot be dispensed with, for in the art of microscopy 

 no autodidact can reach perfection any more than in any other 

 art. Learn to draw, if you desire to see with the microscope. 



A number of devices have been invented for facilitating the 

 drawing of microscopic specimens by means of prismatic glasses. 

 All these are superfluous. If we want to represent a microscopic 

 image on paper, exact in size and shape, we place the paper at 

 the height of the stage of the microscope, very near the right 

 side of the specimen. Looking into the eye-piece with the left 

 eye, keeping the right open, the image is seen projected on the 

 paper, and the point of the pencil can exactly follow the outlines 

 on the image itself. 



A great deal of time is wasted by applying manifold staining 

 methods to microscopic specimens, and they are deceived persons 

 who imagine that the value of a specimen is the greater the 

 nearer it approaches a rainbow appearance. In wasting time 

 by projecting images on screens by means of complicated mechan- 

 isms, many forget that microscopy can really be learned only by 

 handling the microscope, and both eyes and judgment can be 

 educated only by looking into the microscope itself. Too great 

 stress is laid, also, on photographing microscopic specimens. 

 Those who are delighted with nice staining of microscopic 

 specimens, splendid projections on screens, and large micro- 



