416 GLANDERS, ANTHRAX, PYOCYANEUS 
appears to grow best in a somewhat rarefied atmosphere. This has 
been obtained by Fabyan^ by growing the organism on an agar slant 
which is connected by a narrow tube with an agar slant on which 
B. subtilis is growing. B. siibtilis appears to so change the percentage 
composition of the air in the two tubes that B. abortus grows fairly 
readily. He also found that a pressure of three to five atmospheres 
would facilitate the growth of the organism. Theobald Smith^ has 
found that sealing freshly inoculated media with paraffin or sealing 
wax is sufficient. On glucose agar the colonies are round, normally 
colorless and transparent, and have a very glistening, pearly sheen. 
The colonies attain a diameter of from 0.5 to 2.5 mm. The organism 
grows well on blood serum. On gelatin the growth is usually very slow, 
probably because of the lowered temperature of incubation. No 
liquefaction takes place. In milk there is a moderate growth; no acid 
is formed, and no coagulation or peptonization takes place. 
Conditions of Growth.— The organism is killed by an exposure of 59° 
C. for ten minutes.^ 
Products of Growth. — The organism produces no known ferments 
and it produces no acid in glucose or other sugars; on the contrary, 
the reaction on artificial media in which the organism is growing 
becomes slightly alkaline. The organism forms no extracellular toxins. 
Pathogenesis. — Infectious abortion appears to be an infection of the 
fetus in utero and its membranes, which results in the death of the 
fetus and its expulsion, or less commonly its expulsion in a living 
and enfeebled state. The time of expulsion is not definite; it may 
occur early during the period of gestation, or it may not take place 
until the normal completion of pregnancy. Ordinarily there is no 
direct evidence of disease in the mother. 
The lesions in experimental guinea-pigs, which have been described 
very carefully by Fabyan,"* resemble both macroscopically and his- 
tologically those of tuberculosis. As a rule, the muscles are free from 
lesions and there is a tendency for the organism to localize itself in 
the perivascular or subcapsular regions of various abdominal organs. 
The organism may persist in experimental animals for very consider- 
able periods of time without producing manifest symptoms. Fabyan 
has shown^ that the organism may remain alive but latent in guinea-pigs 
for over a year. 
Evans*' has found that B. bronchosepticus and B. abortus are nnich 
alike both in their general cultural reactions and to a degree in their 
agglutination relations. In a recent publication^ she has pointed out 
the very close relationships of B. melitensis and B. abortus. B. 
melitensis (Micrococcus melitensis) also is found to possess common 
> Jour. Med. Res., 1912, 26, 441. 
2 Monograph No. 19, Rockefeller Inst, for Med. Res., November 15, 1923. 
3 Fabyan: Loc. cit., p. 484. * Loc. cit. 
6 Jour. Med. Res., 1913, 28, 81. 
6 Jour. Infee. Dis., 1916, 18, 437; ibid., 1918, 22, 576, 580. 
' Public Health Reports, 1923, 38, 1948. 
