122 A MANUAL OF BACTERIOLOGY 



are difficult to grow by ordinary methods, for studying 

 the phenomena of infection when the micro-organisms are 

 protected from the phagocytes, and for other purposes. 

 A glass rod or small test-tube, according to the size desired, 

 is dipped into a beaker containing the ordinary (not 

 flexible) collodion, is then withdrawn and allowed to dry, 

 and the process is repeated two or three times. In order 

 to detach the collodion from the glass, the whole is dipped 

 for a few seconds alternately into strong spirit and into 

 water, the collodion loosens, and may be easily peeled 

 off the glass. The sack may be sterilised by placing in a 

 test-tube and heating to 150 C. in the hot-air steriliser. 



For the inoculation of animals various methods may be 

 adopted. Thus, after clipping the hair, the organism may 

 be introduced by rubbing into the skin after scarification, 

 or, a small incision having been made through the skin, 

 a small quantity of a culture may be introduced on a 

 platinum needle ; or a broth culture or an emulsion, made 

 with sterilised water or broth, may be injected with a 

 sterilised syringe subcutaneously, intra-peritoneally, or 

 into the muscular or other tissues or organs as required, 

 since the seat of inoculation may have to be varied for the 

 different species to produce their pathogenic effect. For 

 injection purposes a syringe like an antitoxin syringe, 

 i.e. with asbestos or metal piston and glass barrel that 

 can be boiled, may be used. Several sizes, 1 c.c., 2 c.c., 

 and 5 c.c. at least, are required. An all-glass syringe is 

 a still better form, but is expensive. For accurate dosage, 

 the piston-rod should be graduated and have a nut 

 travelling on a screw up and down it. Before use the 

 syringe with the needle should be boiled for ten minutes 

 to sterilise it ; after use it may be well rinsed and again 

 boiled. The needles should be wiped dry and a wire 

 inserted, or they may be kept in a bottle of xylol. 



Guinea-pigs and rabbits are usually inoculated in the 



