SUBCUTANEOUS INOCULATION OF ANIMALS. 207 



Sterilization of the skin is impossible, so that it need 

 not be attempted. If the inoculation is to be by means 

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

 be lifted up and the needle inserted in the way common 

 to this procedure. If a solid culture is to be inocu- 

 lated, a fold of the skin may be taken up with the for- 

 ceps 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 superficial and deep 

 connective-tissue fasciae. These must be taken up with 

 sterilized forceps, and with sterilized scissors incised in 

 a way corresponding to the opening in the skin. The 

 pocket is then to be held open with the forceps and the 

 substance to be inserted is introduced as far back under 

 the skin and fasciae as possible, care being taken not to 

 touch the edges of the wound if it can be avoided. 

 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 to be obtained for the 

 operation, the simple subcutaneous inoculation may be 

 made without the aid of a mechanical holder. 



It is at times, however, more convenient to dispense 

 with the presence of an assistant, and several forms of 

 apparatus have been devised for holding guinea-pigs, 

 rats, rabbits, etc. For small animals, such as mice and 

 rats, the holder suggested by Kitasato is very useful. 

 It is simply a metal plate attached to a stand by a 



