226 NECROBACILLOSIS 
embryonic tissue under the sloughs.” Schmorl reports a fatal 
epizootic among rabbits due to this organism. M’Fadyean, Kitt, 
Olt, Jensen, Johne, Mohler and others have found this organism in 
numerous necrotic lesions in both domesticated and wild animals. 
The organism has been carefully studied in its relation to necrosis 
by Bang, Schmorl and Ernst. Many of the lesions that have been 
found to be due to this organism are known as separate diseases such 
as calf diphtheria, lip and leg ulceration, foot rot in cattle and sheep 
and multiple necrosis in the liver. In addition to these, many 
lesions of a more or less local nature have been attributed to it. 
These have been grouped together under the general heading of 
Necrobacillosis.* 
Geographical distribution. The lesions or diseases caused by 
B. necrophorus are widely distributed in Europe and America. It is 
believed that the organism is an inhabitant of the normal intestine of 
swine and possibly of other animals. Apparently it is widely distrib- 
uted. 
Morbid anatomy. Broadly stated, the lesion is a coagulation 
necrosis with subsequent caseation. There is a slight tendency of the 
organisms to invade the surrounding tissue by a progressive advance, 
or by invading distant parts of the body by metastasis. There may 
be a general intoxication. The lesions are described as sharply 
circumscribed patches of yellowish or dull brown color, sometimes 
greenish-white, homogeneous, rather dry, friable tissue. It usually 
emits a characteristic odor resembling somewhat that of old cheese 
and glue. The line of demarcation between the necrotic and healthy 
tissue is sharp and consists in a narrow zone of hyperemia. The 
organisms are usually found in the outer zone of the necrotic area 
rather than in the central portion. Infection takes place through 
injuries to the tissues and on that account it is an inoculation disease. 
*It has been stated by Mohler that B. necrophorus is essentially 1 pleomorphic 
organism. It varies in size from short coccoid forms to filaments of 100% or more 
in length and varying from 0.75u to 1.54 in width. The longer forms usually appear 
as slender and more or less beaded filaments. In the necrotic tissues they exist in 
large numbers. Frequently one end of the filament may be broad and club shaped 
and the other quite tapering. Involution forms may be present in cultures formed 
in media. The short forms can easily be mistaken for other organisms. Most ob- 
servers have failed to detect motility in this organism but Schmorl found motile 
forms. It is anaerobic and will grow but feebly on the ordinary media. More satis- 
factory results are obtained when it is cultivated on agar-bouillon, agar-gelatin, 
serum-agar, or various combinations of these. It is quite readily destroyed by disin- 
fectants such as five per cent carbolic acid and 1 to 1000 bichloride. Because of the 
character of the death of the tissue it is supposed to produce an extra cellular toxin. 
