POST-MORTEM EXAMINATION OF ANIMALS. 205 



now to be carefully dissected 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. 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 ac- 

 complished 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 genitalia, 

 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, sterilized scissors, is made along the scorched 

 tracks on either side of the thorax, 



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