254 BACTERIOLOGY. 



Make identically the same experiment with a spore- 

 containing culture of anthrax, except that the drop from 

 the mixture will be transferred to 10 c.c. of a mixture 

 of equal parts of ammonium sulphide and sterilized dis- 

 tilled water. After remaining in this for about half a 

 minute, a drop will be transferred to a tube of lique- 

 fied agar-agar, poured into Petri dishes, labelled, and 

 placed in the incubator. Note the results. How are 

 they explained ? 



Prepare a 1 : 1000 solution of corrosive sublimate. 

 To eacii of twelve bouillon tubes containing exactly 10 

 c.c. add : one drop to the first one, two drops to the 

 second, and so on until the last tube has had twelve drops 

 added to it. Mix thoroughly and then inoculate each 

 with one wire loopful of a bouillon culture of staphylo- 

 coccus pyogenes aureus. Place them all in the incubator 

 after carefully labelling them. Note the order in which 

 growth appears. 



Do the same with anthrax spores, with spores of bacillus 

 subtilis, with the typhoid bacillus, and see how the re- 

 sults compare. From these experiments what will be 

 the strength of corrosive sublimate necessary to act as 

 an antiseptic under these conditions for the organisms 

 employed ? 



Make a similar series of experiments, using a five per 

 cent, solution of carbolic acid. 



Determine the antiseptic point in bouillon of the 

 common disinfectants for the organisms with which you 

 are working. 



Determine the time necessary for the destruction of 

 tlie organisms with which you are working, by corro- 



