INSECTICIDES 



345 



Figure 138. A, Tomato worm larva that had been previously 

 killed with KCN and then immersed in a soap and nicotine 

 solution. It will be noted from the dissection that the tracheal 

 tubes do not contain any of the soap solution. B, Tomato worm 

 larva that was immersed alive in a soap and nicotine solution 

 prior to dissection. The tracheal tubes, it will be noted, are 

 partly filled with spray solution. 



