12 BULLETIN 989, U. S. DEPARTMENT OF AGRICULTURE. 



immediately after making, at the end of a month, and in from 12 to 



13 months. In these tests Armour's peptone was substituted for 

 Witte peptone, which was difficult to obtain and not of uniform 

 quality. The same lot of peptone was used throughout, but the meat 

 extract used in the broth was from two different batches, the one 

 employed at the end of the experiments being much darker than the 

 other. The tests were made by two operators using the same ma- 

 terials. 



When freshly made, these six samples gave coefficients varying 

 from 3.12 to 1.31. At the end of a month the same samples gave 

 coefficients ranging from 3.31 to 4.19, and at the end of 12 months 

 they gave coefficients ranging from 3.14 to 4.23. The greatest single 

 variation obtained was a drop from 3.85 when freshly made to 3.14 

 at the end of a year. The average of the coefficients obtained on these 

 six freshly made preparations was 3.88. At the end of the month the 

 average was 3.74, and at the end of 12 months the average was 3.66. 

 This would seem to indicate a deterioration of less than 10 per cent 

 in one year. Taking into consideration the limitations of the test, 

 however, it is evident that this apparent deterioration is practically 

 negligible. 



With respect to dilutions, none of the samples examined were uni- 

 form in killing B. typhosus in -g-^ dilution in 15 minutes, and two 

 failed to kill in 4-^- dilution in this length of time. While it is 

 probably true that a 5-^5- dilution Avould have killed if allowed to 

 remain in contact with the organism for an indefinite time, yet, con- 

 sidering the difficulties of practical disinfection as compared to the 

 artificial test, it is evident that a -^ dilution is too high to recom- 

 mend even for B. typhosus. Under the circumstances it would be 

 much safer to recommend a dilution of not over 1 in 100 when used in 

 cases of typhoid fever. 



In testing the efficiency of the product against Micrococcus aureus, 

 several strains of this organism were employed, as it varies markedly 

 in its resistance to pine-oil preparations. In all, four strains were 

 tested. These were given laboratory numbers 200, 202, 203, and 204. 

 No. 200, a stock strain over five years old, formerly used for class 

 demonstrations, at that time gave typical lesions in the rabbit. At 

 present it is practically nonpathogenic. Nos. 202 and 203 were 

 freshly isolated by the writer from infections in the finger and neck. 

 No. 202 caused abscess formation in the rabbit. No. 203 was non- 

 pathogenic for this animal. No. 204 was a freshly isolated strain ob- 

 tained from the United States Navy medical school through the 

 courtesy of Dr. Pryor. It killed the rabbit, when injected intra- 

 venously in dosage of 2 cc. broth culture, in from one to two days. 

 The lesions produced were those of septicaemia. All the strains pro- 

 duced pigment on potato, and microscopically and culturally seemed 



