EXPERIMENT STATION REPORTS. 203 



symptoms were watering of the eyes and loss of appetite wliicli lasted for 

 several days. 



Blood tests made before each injection showed no change in reaction. 

 None of the negative reactors became positive dnring this time. One 

 of the treated animals aborted February 5, 1923. 



In summing up the results it is only necessary to say that collargol 

 is of doubtful value in tlie treatment of infectious al>ortion, and that 

 its continued use is injurious and dangerous. 



•4. Channels of infeC\tion. 



Although there is fairly definite knowledge of the routes througli 

 wliich Bact. ahortus enters the body of its host, there are yet many 

 questions which have not been settled. Studies and observations on this 

 phase of the problem will be continued. 



5. Control. 



A practical procedure for the control of infectious abortion was pre- 

 sented in the Michigan Agricultural College Quarterlv Bulletin, Vol. 5, 

 No. 4, p. 178, 1923. 



The results of using killed and living (non-virulent) cultures of 

 Bact. abortus the purpose of immunization are now being compiled. No 

 statement of the results will l)e made at this time. 



6. Cultural Studies. 



This is one of the most important phases of the abortion problem. 

 Around the organism itself are centered man}- problems, and new prob- 

 lems are continually presenting themselves. 



Problems along this line whicli are now being studied are the effect 

 of different atmospheric conditions on the growth, antigenic and patho- 

 genic properties of Bact. ahortus, pathogenic and non-pathogenic strains 

 of Bact. ahortus, and a Bact. ahortus like organism. The following ex- 

 periment has been completed and is here given in detail. 



The Effect of a partial Atmosphere of Carhon-dioxide Gas on the Bacteri- 

 ological and Pathogenic Properties of Bact. Ahortus. 



In a former publication it was shown that carbon-dioxide gas plays 

 an important part in the primary cultivation of Bact. ahortus by chang- 

 ing tlie hydrogen-ion concentration of tlie atmosphere in which the 

 organism is placed. 



From our studies and those of others, it appears th^.t this particular 

 atniosi)]ieric condition is found in the fluids surrounding the developing 

 fetus and in the udder, both of which are favorable seats for the locali- 

 zation of Bact. ahortus. A large number of examinatiouG has shown 

 that the hydrogen-ion concentration of fetal fluids, at different periods 

 of gestation, ranges between 0.0 and 7, and the CO. tension by volume 

 between 10 and 15 per cent. The hydrogen-ion concentration of freshly 

 drawn milk has a range of G.G to 7.2 and CO^ tension hy volume between 

 8 and 15 per cent. 



In view of the above facts one experiment was designed to determine 

 what influence a COo tension favorable for the growth of Bact. ahortus 

 would have on its pathogenic, agglutinating and morphological char- 

 acteristics. 



