1 2 APPARATUS. 



incubated can be put into a fruit jar or tin can, which receptacle is 

 placed in the vessel heated by the lamp. 



Emery suggests the use of a Thermos bottle as an incubator. As 

 regards the matter of a low-temperature incubator (for gelatin work) , 

 this is best met. by using a small refrigerator. The ice in the upper 

 part maintains an even cold, and by connecting up an electric lamp in 

 the lower part of the refrigerator we can easily maintain a temperature 

 which only varies one or two degrees during the twenty-four hours. 



With a i6-candle-power lamp a temperature of about 25 C. is 

 mantained (this is too high, being about the melting-point of gelatin), 

 with an 8 candle-power, one about 21 to 23 C., and with a 4-candle- 

 power from 18 to 20 C.; the box being about 20 x 30 x 36 inches. 



When much serum reaction work is done, an electrically run cen- 

 trifuge is of the greatest convenience. 



A filter pump attached to the water faucet, preferably by screw 

 threads, is almost indispensable for filtering cultures,' etc., and for 

 cleaning small pipettes, especially the hgemacytometer pipettes. Such a 

 filter or vacuum pump with a vacuum gauge is more easily controlled. 



BACTERIOLOGICAL PIPETTES. 



With the possible exception of the platinum loop, there is no piece 

 of apparatus so applicable to many uses as the capillary pipette made 

 from a piece of glass tubing. 



These may be made in a great variety of shapes. The one with a 

 hooked end, the Wright tube, is the best apparatus for securing blood 

 for serum tests. The crook hangs on the centrifuge guard and by 

 filing and breaking the thicker part of the tube the serum is accessible 

 to a capillary rubber bulb pipette or to the tip of a haemacytometer 

 pipette. In this way dilutions of serum are easily made. The capil- 

 lary pipette is made by taking a piece of 1/4 in. soft German glass 

 tubing, about six inches long, and heating in the middle in a Bunsen 

 flame, revolving the tubing while heating it. When it becomes soft 

 in the center, remove from the flame and with a steady even pull 

 separate the two ends. The capillary portion should be from eighteen 

 to twenty inches in length. When cool, file and break off this capillary 

 portion in the middle. We then have two capillary pipettes. By 



