220 Infestation of Fungus Cultures by Mites 



either to the cold weather prevailing at the time diminishing the con- 

 centration of Pyridine in the air of the bell-jar, or to the eggs being 

 rather more resistant in this case or under these conditions. 



Series II was exposed to the vapour of commercial Pyridine for two 

 different periods, 16 and 48 hours, in each case in duplicate. The samples 

 were then transferred to Petri dishes and exposed to the moist air of a 

 warm greenhouse for eight hours to free the material from traces of 

 Pyridine as completely and rapidly as possible. The samples were then 

 transferred back to tubes and allowed to stand in a damp atmosphere 

 for 16 to 19 days, small portions being examined from time to time. 



The results of both series are shown in Table IV a. 



Table IV a. 



Showing effect of Pyridine upon Mites and Eggs. 

 {Sample contained about equal numbers of each.) 



Series I. 



