EXPERIMENTS. 453 



Do the same with anthrax spores, with spores of 

 badUus suhtilis, and with the typhoid bacillus, and see 

 how the results compare. From these experiments what 

 will be the strength of corrosive sublimate necessary to 

 act as an antiseptic under these conditions for the organ- 

 isms employed? 



Make a similar series of experiments, using a five 

 per cent, solution of carbolic acid. 



Determine the antiseptic point of the common dis- 

 infectants for the organisms with which you are working. 



Determine the time necessary for the destruction of 

 the organisms with which you are working, by corro- 

 sive sublimate in 1 : 1000 solution, under different con- 

 ditions — with and without the presence of albuminous 

 bodies other than the bacteria, and under varying condi- 

 tions of temperature. 



In making these experiments be careful to guard 

 against the introduction of enough sublimate into the 

 agar-agar from which the Petri plate is to be made to 

 inhibit the growth of the organisms which may not 

 have been destroyed by the sublimate. This may be 

 done by transferring two drops from the mixture of 

 sublimate and organisms into not less than 10 c.c. of 

 sterilized salt solution in which they may be thoroughly 

 shaken for from one to two minutes, or into the solu- 

 tion of ammonium sulphide of the strength given. 



To 10 c.c. of a bouillon culture of staphylococcus 

 pyogenes aureus, or anthrax spores, add 10 c.c. of cor- 

 rosive sublimate in 1 : 500 solution, and allow it to re- 

 main in contact with the organisms for only one-half the 

 time necessary to destroy them (use an organism for 



20* 



