HISTOLOGICAL METHODS 133 



then it should be stretched over a pan, especially devised for the 

 purpose, or nailed to a board. The skin over the abdomen and 

 thorax must then be shaved and sterilized with a solution of 

 bichloride of mercury. The walls should then be seared in a line 

 from the throat to the pubes with a hot knife, and through this 

 line a cut should be made opening up the thoracic and abdominal 

 cavities. 



By means of a hot knife spots must be seared on the various 

 organs, and with another sterile knife cuts should be made into the 

 organs, then through these cuts sterile platinum needles are 

 thrust, and then culture media are inoculated with them. Some- 

 times it is necessary to remove bits of tissue from various organs 

 and place them in culture media. In the recovery of the tubercle 

 bacillus from animals this procedure is necessary. Great care 

 must be taken in making the culture and all tubes should be 

 carefully stored. It is of great importance to make smears on 

 cover-slips as well as cultures, from the heart cavities, liver, 

 kidneys, peritoneal cavity, etc., and stain them directly with 

 Gram stain. It is sometimes necessary to inject cultures, or 

 bits of nerve tissue from a rabies case into the brain. To do 

 this, remove under strict aseptic precautions, a button of bone 

 from the skull by means of a trephine. It should not be forgotten 

 that animals inoculated and killed or dying after infection may 

 present dangerous material to the laboratory personnel. After 

 an autopsy, a strong disinfectant should be generously spread 

 over all parts of the animal and autopsy tray. 



Histological Methods 



Sections of tissues from infected animals are often examined and 

 stained by appropriate methods. To demonstrate bacteria, the 

 tissues should be hardened in alcohol or formaldehyde solution 

 (4 percent), and imbedded in celloidin, then cut into sections and 

 mounted in the following different ways : 



