Apr. 15, 1915 Disinfection of Hides 



A further series of experiments having given unsatisfactory results, 

 it was deemed advisable to undertake comparative tests of infected 

 pieces of hide prepared by several different methods. 



Further experiments were thereupon made to compare the infectivity 

 of pieces of hide dried (i) in an electric oven at 44° C. for 40 hours; (2) in 

 an incubator at 37° C. for 24 hours (spores in blood clots) ; and (3) in a 

 desiccator over sulphuric acid at a temperature of about 10° C, the 

 desiccator being exhausted of air down to a pressure of about 6 cm. of 

 mercury, time of drying, 48 hours. 



Of the above only those pieces dried at a low temperature proved 

 infectious, the guinea pig inoculated dying after one week. As a guinea 

 pig inoculated by pure culture also remained alive for a week, it seemed 

 that the process of drying at 10° C. in a vacuum over sulphuric acid had 

 not appreciably diminished the virulence of the spores. This process was 

 therefore used in the preparation of all further test pieces of hide. 



Previous experiments had shown a difference between the two strains 

 of guinea pigs which had been used in these experiments, one strain be- 

 ing much more susceptible to infection by anthrax than the other. The 

 comparatively low virulence of the pure culture mentioned above seemed 

 to be due to passage through the less resistant strain of guinea pigs. 

 Beginning, therefore, with a culture which had not been so treated, suc- 

 cessive inoculations were made with the more resistant strain of guinea 

 pigs until cultures of satisfactory virulence and vitality were obtained. 



V. EXPERIMENTS UPON INFECTED PIECES OF HIDE DRIED AT IO° C. 



A lot of pieces of hide were prepared as follows: Pieces of 2K gm. in 

 weight were washed and dried. These were infected by a suspension 

 made from a 7-day agar culture, in the following manner: Pieces were 

 placed in the suspension, hair side down, and allowed to soak for 10 

 minutes, and then 0.2 c. c. of the suspension was dropped on each. 

 These pieces were left in Petri dishes in the ice box for half an hour with 

 covers of dishes on. At the end of that time the dishes were placed in a 

 desiccator over sulphuric acid and the covers raised. The desiccator was 

 then exhausted of air and put into the ice box, where it remained 48 

 hours at a temperature of 10° C. The pieces of hide were then removed 

 and kept at room temperature until used. A guinea pig inoculated with 

 the pure culture used for infecting these pieces of hide died in four days. 

 Using the pieces of hide prepared as described, the following experiments 

 were performed : 



In experiment 18, pieces of hide were exposed to the disinfectant for 

 24 hours, followed by a saturated salt solution for i hour. They were 

 then treated with a i per cent sodium-sulphid solution for 2 hours and 

 washed with sterile water. Material was then scraped from the surface 

 of each and inoculated into a guinea pig. The results are given in Table 

 VIII, experiment 18. 



