Chloropicrin 



Control 



Chloropicrin 



Sodium Cyanide 



FlG. 41. — Beneficial effect of partial sterilization on tomatos grown in pots. The 

 second from the left is the control plant in unsterilized soil ; the others have 

 been treated with the agents named (Chloropicrin and Sodium Cyanide). 



Chlordinitrobenzene Control Dichlotcresol Cresol 



Fig. 42. — Beneficial effect of dichlorcresol. Harmful effect ol 

 chlordinitrobenzene, which is too potent an agent at this 

 strength (0*27 per cent.). 



