USE OF THE MICROSCOPE 5 



but before doing this the student shoiild endeavour to familiarise himself 

 with the use of the microscope, and at the same time learn to recognise some 

 of the chief objects which are liable to occur accidentally in microscopic 

 specimens. On this account it has been considered desirable to introduce 



FIG. 3. ORGANIC MATTERS FREQUENTLY PRESENT IN DUST. (Heitzmann.) 



S, fibres of silk ; C, of cotton ; L, of linen ; W, of wool ; F, feather ; St, starch-granules ; Cr, 

 cork ; 0, spores of mildew ; At, mycelium or threads of mildew ; Me, micrococci ; B, bac- 

 teria ; Lt, leptothrix filaments (500 diameters). 



directions for the examination of starch-gramiles, air-bubbles, linen, cotton, 

 and woollen fibres, and the usual constituents of the dust of a room, into the 

 first practical lesson. 



