EXPERIMENTS. 621 



To each of two tubes — the one containing 10 c.c. 

 of normal salt-solution, the other of bouillon — add as 

 much of a spore-containing culture of anthrax bacilli 

 as can be held upon a loop of platinum wire. Dis- 

 tribute this uniformly through the medium, and then 

 add exactly 10 c.c. of a 1 : 500 solution of corrosive 

 sublimate. Mix thoroughly, and at the end of five 

 minutes transfer a drop from each tube to tubes of 

 liquefied agar-agar. Pour these immediately into 

 Petri dishes. Label each dish carefully and place them 

 in the incubator. Note the results at the end of twenty- 

 four, forty-eight, and seventy-two hours. How do 

 you explain them ? 



Make identically the same experiment with the same 

 spore-containing culture of anthrax bacilli, except that 

 the drop from the mixture is to be transferred to 10 c.c. 

 of a mixture of equal parts of ammonium sulphide and 

 sterilized distilled water. After remaining in this for 

 about half a minute, a drop is to be transferred to a 

 tube of liquefied agar-agar, poured into Petri dishes, 

 labelled, and placed in the incubator. Note the results. 

 Do they correspond with those obtained in the pre- 

 ceding experiment? How are the differences ex- 

 plained ? 



Prepare a 1 : 1000 solution of corrosive sublimate. 

 To each of twelve tubes containing exactly 10 c.c. of 

 bouillon add one drop to the first, 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 wdre-loopful of a bouillon culture of 

 staphylococcus pyogenes aureus. Place them all in the 



