44 MICRO-ORGANISMS AND DISEASE [CH. ili 



hand holds the bulb of the pipette, the other holds one end, 

 and putting at some distance from this end the tube into an 

 ordinary flame and quickly drawing it out, a point of extreme 

 fineness can be made. The same is done with the other end. 

 Such a pipette can be considered as practically closed at 

 both ends. 



Amongst the apparatus useful in bacteriological work the 

 autoclave ^ deserves a place ; it is a cylindrical metal chamber 

 heated by gas flame, and containing a small amount of 

 water ; the lid can be hermetically screwed down ; the tem- 

 perature of the steam developed inside is under pressure 

 easily raised beyond the boiling point of water, as when any 

 fluid culture medium {e.g. nutrient Agar as described above) 

 is to be heated to say 110-115° C. ; one atmosphere pres- 

 sure corresponds to this temperature of 110-115° C. 



Platinum needles, platinum loops, or platinum lancets two 

 to three inches long are fastened (melted) either in glass rod 

 handles or in wooden handles by means of a long metal 

 cylinder ; in the latter case the sterilising by heat of the near 

 end of the needle can be just as easily carried out as of the 

 glass rod, though a cracking and breaking of this latter is 

 avoided. Copper ovens of various sizes are used for the 

 heating (melting) of paraffin, &c., where a constant definite 

 temperature is to be maintained. 



The serum inspissator for the solidification of serum which 

 is most useful is the one of Hueppe's design as shown in 

 Fig. 10. 



Trays of wood or tin are useful for obtaining gelatine, or 

 Agar tubes with large slanting surface during cooling (setting) 

 are shown in Fig. 9. 



' Sold by Wiesnegg in Paris. 



