228 Infestation of Fungus Cultures by Mites 



saturated with vapour, the slowing down of the reaction being un- 

 doubtedly due to this cause. 



Table VI. 



Showing Toxic Effect of increasing doses of Pyridine and ' 

 Aniline to Cheese-mites (T. longior). 



All the mites after treatment with Pyridine extremely sluggish, and appear paralysed. 



Aniline. Exposure 3 hours. 



All the live mites after Aniline treatment more active than in case of Pyridine. All flasks 

 saturated from D downwards before treatment. C doubtful. 



On these curves the 50 per cent, survivor points correspond to 

 21 millionths of a gramme-molecule of Aniline and 63 of Pyridine, 

 indicating that at this point, the most suitable one for purposes of com- 

 parison, Anihne is about three times as toxic as Pyridine. Taking the 

 Aniline curve as a whole, the break towards the end due to the fact that 

 from about 35 millionths of a gramme-molecule upwards the air is 

 saturated with vapour, shows that its toxic inefficiency is not due to an 

 intrinsic lack of poisonous properties, but that its low vapour pressure 

 limits to this extent its concentration in air at ordinary temperatures. 



