THE DETECTION OF BACTERIAL PATHOGENICITY 237 



learned and that the autopsy procedure be treated with considerable 

 respect. It should always be remembered that examination of a dead or 

 dying animal may be a hazardous operation because the cause of death 

 remains to be established. For this reason a series of standardized and 

 properly thought-out safety and aseptic precautioiis should always be 

 followed even when autopsying animals which have died following inocu- 

 lation of a known pathogen. As stated above, it not infrequently 

 happens that following injection of known cultures, the animal may die 

 from some supravening agent and one which may be pathogenic for man. 



The following information is sought at autopsy and in subsequent 

 workup of the materials: the cause of death, the type of distribution and 

 histopathology of the lesions, distribution of the infected organism, 

 changes that may have taken place in the microorganism itself, and 

 finally, if antibodies have developed. 



If an autopsy cannot be made immediately after death, the carcass 

 should be refrigerated. It is well to cover the operating surface with a 

 germicide-soaked paper or cloth towel, and before the animal is opened, 

 the entire carcass should be washed down with disinfectant. In the case 

 of small animals the entire carcass may be immersed into a jar of some 

 disinfectant, such as lysol. Carefully examine the area of the site of 

 inoculation, if any. Then with a sharp scissors make a small keyhole 

 opening through the skin but not penetrating the muscle wall over the 

 lower peritoneum. By blunt dissection separate the skin from the under- 

 lying muscle. When this is completed, it is a relatively simple matter to 

 open a median ventral incision, using the scissors and pulling the skin 

 back on each side. It is not advisable to use a scalpel for the autopsy of 

 small animals because of the inherent danger to the operator and because 

 it is often too easy to cut deeper than is intended and to contaminate an 

 area. After the peritoneal muscularis has been exposed, the surface 

 should be sterilized by swabbing with tincture of iodine, following which, 

 a fresh set of instruments is used to continue the operation. Open the 

 peritoneal cavity, leaving the pleural cavity intact. Examine the perito- 

 neal contents, paying particular attention to the surface of the large 

 organs, such as the liver and spleen. Make note of the size of the spleen, 

 since splenomegaly often accompanies acute infections. Using separate 

 instruments, remove portions of the tissues for cytological and cultural 

 study to sterile petri plates, which should be kept at hand for this pur- 

 pose. Do not make any smears or cultures of the tissues until the autopsy 

 is completed, as this can usually be done at leisure. If it is desired to 

 remove exudates, this can be done by means of a glass pasteur pipet or 

 syringe. When the examination of the peritoneum is completed, the 

 thoracic cavity is opened, care being taken not to cut the diaphragm or 

 pierce the lungs. After intracerebral inoculation it is sometimes desirable 



