72 



Journal of Agricultural Research 



Vol. IV, No. I 



Table V. — Germicidal efficiency of mercuric chlorid, with and without formic acid, by 

 the rod method, with addition of defibrinated blood — Continued. 



BXFQRIMBNT S" 



Rod 



No. 



Disinfectant (lo c. c.) and dilution. 



Time of 

 exposure, 



Mercuric chlorid (i:2,ooo)+formic acid (i per cent). 

 Mercuric chlorid (1:3,000) + formic acid (i percent). 

 Mercuric chlorid (i:4,ooo)+formic acid (i per cent). 



Mercuric chlorid (1:1,000) 



Control rod 



C) 



Orowth. 

 Do. 

 Do. 

 Do. 

 Do. 



EXPERIMENT 9" 



Mercuric chlorid (i:i,ooo)+formic acid (i per cent) 

 Mercuric chlorid (1:2,000)+ formic acid (i per cent). 

 Mercuric chlorid (1:3 ,000) + formic acid (i per cent) 



Mercuric chlorid (i:i,ooo) 



Control rod 



(*-) 



No growth. 

 Growth. 



Do. 



Do. 



Do. 



o The quantity of disinfectant used in experiments 7, 8, and 9 included i c. c. of defibrinated blood. 

 & Not exposed. 



The discrepancy between the results of experiment 7 and those of 

 experiments 8 and 9 appeared to be due to the use of a culture only 

 7 days old for making the spore suspension used in experiment 7, while 

 the cultures used in experiments 8 and 9 were 17 and 22 days old, 

 respectively. 



In all these experiments spore suspensions were examined microscopi- 

 cally to make certain that plenty of spores were present, and it was noted 

 that where cultures were less than 10 days old the suspensions generally 

 contained a greater number of bacilli in relation to the spores than sus- 

 pensions made from cultures 2 to 3 weeks old. The older cultures were 

 therefore better adapted for this work. 



The results of these experiments and a number of other similar experi- 

 ments indicated that the A. M. S. strain of Bacillus anthracis was much 

 more vigorous than the B. A. I. strain, which was used in experiments i 

 to 4, and consequently was better suited for the purpose of this work. 

 The following experiments, in which pieces of infected hide were emploj^ed, 

 were therefore carried on with spores of the A. M. S. strain. 



m. EXPERIMENTS UPON PIECES OF HIDE INFECTED WITH SPORES OF THE ARMY 

 MEDICAL SCHOOL STRAIN OF BACILLUS ANTHRACIS AVITHOUT NEUTRALIZATION OF 

 DISINFECTANT 



Some of the pieces of hide were prepared by a method essentially the 

 same as that described by C. W. Ponder (9, 10), the details being as 

 follows: The test preparations were made by cutting out pieces of hide 

 so that each piece weighed about 2^ gm. Blood was drawn from the 

 ear of a rabbit and a good-sized drop allowed to fall on the center of 

 the hair side of each piece. Before clotting occurred a loopful of a sus- 

 pension of anthrax spores was mixed thoroughly into the drop of blood. 



