626 



APPENDICES. 



Test-tube Stands. The ordinary wooden pattern, or the 

 metallic folding stands, are called into use 

 for holding cultivations. Pegged racks are 

 also recommended for draining test -tubes 

 after washing. 



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, ex- 

 amining cultivations, etc., consists of two or 

 three inches of platinum wire fixed to the 

 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 



FIG. 254. WIRE CAGE 

 FOR TEST-TUBES. 



end of a glass rod. 



FIG. 255. PLATINUM NEEDLES; STRAIGHT, HOOKED, LOOPED. 



a Bunsen. burner, and a piece 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 



FIG. 256. DAMP CHAMBER FOR PLATE-CULTIVATIONS. 



inoculating test-tubes of nutrient jelly. For other purposes the 

 needles may be bent at the extremity into a small hook, and 

 others provided with a loop (Fig. 255). 



