APPARATUS, MATERIAL, AND REAGENTS. 25 



Caoutchouc Caps. These are caps for fitting 

 over the cotton wool plugs, and may be used in 

 different sizes for test-tubes and stock-flasks. 



Platinum Needles. A platinum needle for 

 inoculating nutrient media, examining cultivations, 

 etc., consists of two or three inches of platinum 

 wire, fixed to the end of a glass rod. Several of 

 these needles should be made, with platinum wire, 

 of various thicknesses. A piece of glass rod, 

 about seven inches long, is heated at the extreme 

 point in the flame of a Bunsen burner, and a piece 



FIG. 6. PLATINUM NEEDLES. 



of platinum wire, held near one extremity with 

 forceps, is then fused into the end of the rod. 

 Some needles should be perfectly straight, and 

 kept especially for inoculating test - tubes of 

 nutrient jelly. For other purposes the needles 

 may also be bent at the extremity into a small 

 hook or a loop* (Fig. 6) 



Tripod Levelling-stand. A triangular wooden 

 frame supported upon three screw-feet, which 



* A looped platinum needle is called in Germany an " ose," a term 

 which, on account of its brevity, may be conveniently adopted. 



