152 BACTERIOLOGY. 



previously been sterilized. This pocket must be cut 

 large enougli 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, and in- 

 cised in a way corresponding to the skin. The pocket 

 is then to be held open with the forceps and the sub- 

 stance 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 be then simply pulled together and 

 allowed to remain. No stitching or efforts at closing 

 it are necessary. 



During manipulation the animal must be held quiet. 

 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. 



For mice, however, a holder is of much convenience. 

 This piece of apparatus consists of a bit of board of about 

 7 x 10 cm. and 2 cm. thick, upon which is tacked a hol- 

 low, tapering roll of wire gauze, a truncated cone of 

 about 6 cm. long and of about 1.5 cm. in diameter at 

 one end and 2 cm. at its other end. 



This is tacked upon the board in such a position that 

 its long axis runs in the long diameter of the board, 

 being equidistant from its two sides. Its small end is 

 placed at the edge of the board. The mouse is taken up 

 by the tail by means of a pair of tongs and allowed to 

 crawl into the smaller end of this wire cone. When so 

 far in that only the root of the tail projects, the animal 

 is then fixed in this position by a clamp and thumb- 



