320 BACILLUS OF INFECTIOUS ABORTION 



with paraffin. While the bacillus in ordinary air does not grow up 

 "to the surface of the solid culture media, the presence of an atmosphere 

 rich in oxygen favors growth and makes it much more abundant. 

 This is true even when an excess of carbon dioxide of from 4 to 5 per 

 cent, is present. Bang found two optima of growth, one in the presence 

 of atmospheric air, and one in the presence of almost 100 per cent, 

 oxygen. If the air above the solid culture medium is rarefied to a 

 certain degree the growth reaches to the surface; if the rarefication 

 becomes excessive, growth ceases entirely. 



MacNeal and Kerr have recently found the bacillus of contagious 

 abortion in some cases of abortion in cows in Illinois. In order to 

 isolate this peculiar microorganism, they have made use of a new 

 plate or Petri dish method devised by Nowak, which is as follows: 

 Ordinary agar is melted and cooled to 50 C.; then mixed with 

 about one-fourth its volume of naturally sterile blood serum, and 

 poured into sterile Petri dishes, where it is allowed to solidify. The 

 piece of placenta or other material from the abortion is streaked over 

 a number of Petri dishes in the manner generally employed in preparing 

 streak dilution cultures. The plates are then incubated for twenty- 

 four hours at 37 C., to allow contaminating aerobic bacteria to 

 develop. Colonies which have developed after twenty-four hours are 

 marked with a ring on the glass by the aid of a glass pencil, India 

 ink, or a cut-out label etc. The plates are then put into an anatomic 

 jar, Novy jar, or desiccator, with a culture of the Bacillus subtilis. 

 About one square centimeter of subtilis culture is to be used for each 

 15 c.c. of air volume of the jar. The jar is then closed and kept in 

 the incubator for three days. The growth of the subtilis bacillus is 

 used to absorb some of the oxygen of the air in the jar and to bring 

 about those conditions which favor the growth of the abortion bacillus. 

 If any of these are present they develop as transparent colonies with 

 the characteristics already described. 



Resistance. The bacillus dies out rapidly in pure cultures (in about 

 two weeks). It is killed at 55 C. in three minutes, in corrosive 

 sublimate 1 to 2000 in fifteen seconds, in 1 per cent, carbolic acid 

 in one minute, in 2 per cent, acetic acid in two minutes, and in 1 per 

 cent, acetic acid in twenty minutes. It can remain alive and virulent 

 in dried uterine exudate where it had its natural habitat, in the 

 uterine cavity, and in dead embryos for many months. 



Diagnosis. McFadyean and Stockman have recently studied the 

 distribution and diagnosis of epizootic abortion in Great Britain. 

 They ascertained the existence of the disease in fifty-five farms, 

 distributed over thirty-six counties. They examined 51 feti and found 

 the bacillus discovered by Bang in 22 feti. In 35 fetal membranes 

 they obtained the bacillus in 33 specimens, while they failed in only 2; 

 hence they consider the examination of the membranes for the 

 presence of the Bang bacillus a more trustworthy procedure than the 

 bacterial examination of the fetus. The two investigators attempted 



