160 BACTERIOLOGY. 



away, not only from the abdomen and thorax, but from 

 the axillary, 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 abdomen 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 be made only 

 through surfaces that have been sterilized. This is best 

 accomplished by the use of a broad-bladed common knife 

 which can be heated in the gas-flame. The blade is to be 

 heated quite hot, and 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 organisms that may have 

 fallen upon the surface from without, 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 geuitalia, 

 is to be made without touching the internal viscera. 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 pair 

 of heavy scissors, which have been sterilized, is made 

 along the scorched tracks on either side of the thorax. 



After this the whole anterior wall of the thorax may 



