2 PRACTICAL HISTOLOGY [l 



is moved in this way, the fine adjustment is said to 

 be used. 



2. A mounted specimen 1 is given you for examina- 

 tion, the piece of glass on which it is placed is the 

 slide, the thin piece of glass covering the specimen is 

 the cover-slip. 



Screw the |rd inch objective on to the microscope 

 and put the longer ocular, No. 2, into the tube. Dust 

 the mirror, if that is necessary : use the concave 

 mirror if there is no sub-stage condenser; use the 

 flat mirror if there is a sub-stage condenser. Place 

 the slide on the stage of the microscope so that the 

 specimen is on the centre of the hole in the stage. 



Lower the tube by means of the coarse adjustment, 

 so that the lower lens of the objective is about half-an- 

 inch from the specimen ; look through the ocular, and 

 shift the mirror till the maximum amount of light is 

 obtained ; use a diaphragm beneath the stage with an 

 aperture nearly as large as that in the stage. Look 

 through the ocular again and slowly lower the tube 

 until the specimen comes into view; focus with the 

 fine adjustment till the maximum distinctness of the 

 specimen is obtained. Note carefully the distance of 

 the lower end of the object-glass from the specimen. 



Substitute ocular No. 4 for ocular No. 2, and lower 

 the tube with the fine adjustment, until the specimen 

 is again distinctly seen ; the magnification will be 

 greater than with ocular No. 2. 



The magnification of the frd objective with the 

 lower ocular will probably be 60 to 70 diameters, with 



1 This may be a section of tissue with blood vessels injected, e.g. of 

 kidney. 



