BLACK LEG 247 
It is more difficult to differentiate between black leg and malignant 
edema as both produce crepitant edematous swellings. The bacillus 
of malignant edema forms long chains which are never met in cultures 
of black leg. It is also more actively motile, longer and more wavy 
than that of black leg. 
Animal inoculation. In guinea pigs inoculated in the deeper sub- 
cutaneous tissues with pure cultures of black leg bacteria or with bits 
of tissues from the affected area of an animal dead from the disease, 
death ensues in from‘one to two days. It is preceded by a rise of 
temperature, loss of appetite and general indisposition. The site of 
inoculation is swollen and painful and drops of bloody serum may 
sometimes be seen exuding from it. At autopsy the subcutaneous 
cellular tissues and underlying muscles present a condition of emphy- 
sema and extreme edema. The edematous fluid is often blood stained 
and the muscles are of a blackish or blackish-brown color. The 
lymphatic glands are markedly hyperemic. The internal viscera 
present but little alteration visible to the naked eye. In the blood 
stained serous fluid about the point of inoculation short bacilli are 
present in large numbers. These often present slight swellings at the 
middle or near the end. They are not seen as threads but lie singly 
in the tissues. If the autopsy is made immediately after death, these 
organisms may not be detected in the internal organs, but if not made 
until after a few hours, they will be found there also. In early autop- 
sies only the vegetative forms of the bacilli may be found, but a few 
hours later spore-bearing rods may be detected. 
Prevention. In checking the spread of the disease it is very import- 
ant wherever it is possible to remove the well animals from the infected 
field. The swellings should not be opened and the discharge scattered 
over the field. The dead animals should be burned if possible, other- 
wise buried deeply and covered well with lime as soon as possible after 
death. Birds and other animals should not be allowed to feed upon 
the carcasses and the skin should not be removed. Every precaution 
to restrict the spread of the bacteria of this disease should be taken. 
It is very desirable to thoroughly disinfect the ground where the 
animal lay at the time of death. The spores are very resistant both 
to disinfectants and the natural destructive agencies such as sunlight 
and drying. It is not wise to use land upon which animals have 
contracted the disease for grazing purposes for susceptible species. 
According to Jensen, it is possible to reduce the infectiousness of 
the soil in the localities where black leg exists by draining the soil, 
