SKIN-DISINFECTION 325 



a needle and drawing it across the plates. A growth now 

 results. We have here an experiment in which organisms 

 which have been exposed to sublimate for a much shorter 

 time than necessary to destroy them, when transferred 

 directly to a favorable culture-medium do not grow, and 

 yet, when the same organism which has not been exposed 

 to sublimate at all is planted upon the same medium it 

 does grow. How is this to be accounted for? 



SKIN-DISINFECTION. 



With a sterilized knife scrape from the skin of the hands, 

 at the root of the nails, and under the nails, small particles 

 of epidermis. Prepare plates from them. Note the results. 



Wash the hands carefully for ten minutes in hot water and 

 scrub them during this time with soap and a sterilized 

 brush. Rinse them in hot water. Again prepare plates 

 from scrapings of the skin on the fingers, at the root of the 

 nails, and under the nails. Note the results. 



Again wash as before in hot water with soap and brush, 

 rinse in hot water, then soak the hands for five minutes in 

 1 : 1000 corrosive sublimate solution, and, as before, prepare 

 plates from scrapings from the same localities. Note the 

 results. 



Repeat this latter procedure in exactly the same way, 

 but before taking the scrapings let some one pour ammonium 

 sulphide over the points from which the scrapings are to 

 be made. After it has been on the hands about three minutes 

 again scrape, and note the result upon plates made from the 

 scrapings. 



Wash as before in hot water and soap, rinse in clean hot 

 water, immerse for a minute or two in alcohol, after this in 



