406 APPENDIX. 



of which is a thistle-head funnel filled with sterilized cotton wadding. The 

 other end dips down nearly to the level of the nutrient medium. Through the 

 other hole a short glass tube passes just to the other side of the bung ; its 

 outer end is slightly bent, and is fitted with a piece of indiarubber tubing, 

 on which a pinch clip fits. Into the other end of the rubber tubing a wash- 

 bottle nozzle is fitted. The gelatine is first filtered into this flask, and the 

 whole is sterilized as usual, a piece of cotton wadding or paper tied in position 

 serving to keep dust away from the nozzle. When tubes or small flasks are to 

 be filled the gelatine is melted, the flask, inverted, is fitted into a retort stand 

 ring, the nozzle is allowed to fall into the mouth of the vessel to be filled 

 and the pinch clip is compressed. If care be taken to cover the nozzle 

 carefully each time that the flask is used, there is very little danger of con- 

 tamination from without. Fluid media may also be kept in these flasks, 

 but Lister's flasks are perhaps adapted better for this purpose. 



Apparatus used for Inoculating Animals or Artificial Nutrient Media. 



Inoculating needles are made of pieces of platinum wire mounted in glass 

 rods; these are of various shapes (i) perfectly straight, (2) with a loop for 

 inoculating liquids, or (3) with a hook or short rectangular limb for 

 inoculating extensive free surfaces, such as "oblique" blood serum, agar- 

 agar or gelatine, potatoes, &c. These are usually allowed to stand upright 

 in a wide-mouthed bottle in which a piece of cotton wadding is placed. 

 Before it is used the wire should be heated to a white heat ; the glass rod 

 is also thoroughly heated ; the needle is then allowed to cool and a small 

 quantity of the substance to be inoculated is taken on the end of the wire and 

 introduced as required. Where the inoculations have to be made into 

 narrow-mouthed flasks or tubes, short fragments of platinum wire are 

 often used. These, held in a pair of forceps, are heated in a flame. When 

 they are quite cool, one of them is dipped into the inoculating fluid and then 

 dropped into the fluid culture medium. Capillary tubes, five or six inches 

 long, pipettes, or glass needles, may be used for the same purpose. Where 

 large quantities of fluid have to be inoculated, the Pasteur pipette, which 

 consists of a piece of tubing with one end drawn out into a fine capillary 

 tube, the other being plugged with sterilized cotton wadding, is often used. 

 These capillary pipettes are always kept closed at the ends. All that is 

 necessary before using them is to snip off the end with a pair of sterilized 

 forceps, pass the glass once or twice through the flame, allow it to cool, and 

 then draw up the amount of inoculating fluid required and inject into the 

 media, tissues, or vessels. 



Cantani uses a similar pipette, but fits it up as follows : Over the end 

 of the pipette that is filled with cotton wadding he fits a piece of india- 

 rubber tubing. Into the other end of this latter is placed a piece of glass 

 tubing, in which is a hole at the side ; then comes another piece of india- 

 rubber tubing, then a glass mouthpiece, and the apparatus is complete. 

 When the apparatus is to be used, the end of the pipette is broken off after 

 being carefully heated and allowed to cool ; it is then introduced into the 

 inoculating fluid, a finger is placed over the orifice in the side of the middle 

 glass tube, and by suction the required quantity of fluid is drawn into the 

 pipette ; the finger on the opening controlling the pressure or vacuum. To 

 inject, reverse the process. As soon as the finger is removed the pressure 

 within the tube becomes equal to that outside, however much suction or 

 blowing there may be, and the operation stops. It is a valuable apparatus, 



