220 BACTERIOLOGY. 



scissors. The whole of the skin is now to be carefully 

 dissected away, not only from the abdomen and thorax, 

 but from the axilliary, inguinal, and cervical regions, and 

 the fore and hind legs as well. The skin is then pinned 

 back to the board so as to keep it as far from the abdo- 

 men and thorax as possible, for it is from the skin that 

 the chances of contamination are greatest. 



It now becomes necessary to proceed very carefully. 

 All incisions from this time on are to made only 

 through surfaces that have been sterilized. The sterili- 

 zation is best accomplished by the use of a broad-bladed 

 common knife that has been heated in the gas-flame. 

 The blade, made quite hot, is to be held upon the 

 region of the linea alba until the skin at that region 

 begins to burn ; it is then held transverse to this line 

 over about the centre of the abdomen, thus making two 

 sterilized tracks through which the abdomen may be 

 opened by a crucial incision. The sterilization thus 

 accomplished is, of course, directed only against organ- 

 isms that may have fallen upon the surface from with- 

 out, and it therefore need not extend deep down through 

 the tissues. 



In the same way two burned lines may be made from 

 either extremity of the transverse line up to the top of 

 the thorax. 



With a hot scissors the central longitudinal incision, 

 extending from the point of the sternum to the geni- 

 talia, is to be made without touching the internal vis- 

 cera. The abdominal wall must therefore be held up 

 during the operation with sterilized forceps or hook. 



The cross incision is made in the same way. When 

 this is completed, an incision through the ribs with a 



