FOWL CHOLERA 39 
warrant handling such outbreaks by methods other than those used 
to combat cholera unless biologic products are used. 
Treatment. The treatment of individual sick birds is not rec- 
ommended, and their immediate slaughter is advised. 
Immunization. Pasteur in his memorable studies on immuni- 
zation against disease first worked with the fowl cholera organism 
in an attempt to produce an immunity against the disease caused 
by this organism. He utilized in his experiments cultures of the 
fowl cholera bacterium which he believed had become attenuated 
by exposure to air for a period of several months. His favorable 
results laid the foundation for the further study of the control 
of disease by the utilization of the specific causative organism as 
an agency of prevention. Kitt, Cogny, Vages and others working 
along the lines pursued by Pasteur have failed to substantiate his 
findings. However, it is quite possible that Pasteur worked with a 
strain of the fowl cholera organism which had immunizing value. 
Such an inference may be drawn through the researches of Hadley 
who demonstrated that a particular strain of the fowl cholera or- 
ganism designated strain 52, although practically avirulent, had the 
power, when injected in the live state, of conferring immunity to 
rabbits against the subsequent injection of a highly virulent strain. 
These findings were, to a considerable degree, confirmed by Gal- 
lagher who also found that fowls acquired a marked resistance to 
comparatively large amounts of a virulent culture following the 
injection of immunizing strain 52. At the same time the latter’s 
experiments with killed cultures of several strains of the fowl 
cholera organism, including strain 52, as immunizing agents gave 
negative results. In each case fowls injected with bouillon cul- 
tures of organisms killed by heating at 60° C. for 1 hour, by car- 
bolizing to .5 per cent or by mixing with ether in equal parts, 
failed to show resistance to a subsequent injection of .000,000,001 
e.c. of a virulent strain. 
Mack failed to produce immunity by the use of killed organisms 
against artificial infection but claims successful results in a num- 
ber of natural outbreaks. The use of an avirulent living organism 
with immunizing properties offers the most promising method of 
prevention. One c.c. of a 24 to 48 hour bouillon culture grown 
at 37° C. is injected subcutaneously. The point most convenient 
for injection is the unfeathered area of the breast beneath the 
wing. 
It is possible to produce an antiserum by injecting a horse re- 
