236 BA CTERIOLOG Y. 



dirty, it may be scrubbed with soap and water. Steriliza- 

 tion of the skin is practically impossible, so it need not 

 be attempted. If the inoculation is to be made by means 

 of a hypodermic syringe, then a fold of the skin may be 

 lifted up and the needle inserted in the usual way. If a 

 solid culture is to be inoculated, a fold of skin may be 

 taken up with forceps and a pocket cut into it with 

 scissors which have previously been sterilized. This 

 pocket must be cut large enough to admit the end of the 

 needle without its touching the sides of the opening as it 

 is inserted. Beneath the skin will be found the super- 

 ficial and deep connective-tissue fasciae. These must be 

 taken up with sterilized forceps, and with sterilized scis- 

 sors incised in a way corresponding to the opening in the 

 skin. The pocket is then to be held open with the for- 

 ceps and the substance to be inserted is introduced as 

 far under the skin and fasciae as possible, care being 

 taken not to touch the edges of the wound if it can 

 be avoided. The edges of the wound may then be 

 simply pulled together and allowed to remain. No 

 stitching or efforts at closing it are necessary, though a 

 drop of collodion over the point of operation may serve 

 to lessen contamination. 



During manipulation the animal must be held still. 

 For this purpose special forms of holders have been 

 devised ; but if an assistant is at hand, the simple sub- 

 cutaneous inoculation may be made without the aid of 

 a mechanical holder. 



It is at times, however, more convenient to dispense 

 with an assistant ; one of several forms of apparatus that 

 have been devised for holding mice, guinea-pigs, rats, 

 rabbits, etc., may then be used. For small animals, such 

 as mice and rats, the holder suggested by Kitasato is very 



