Kenneth M. Smith 



49 



As has been mentioned already in this paper the damage to the apple 

 fruit itself is very considerable, owing to the fact that the growth of the 

 apple is almost entirely stopped by the death of the cells of the exterior; 

 in cases where one side only is punctured by the bug, the other side of 

 the apple continues to grow to a certain extent thus causing a greatly 

 distorted fruit. 



Fig. 5. Section of the salivary gland of Lygus pabulinus, 4 fj. thick, ^th oil immersion, 

 ocular 4. 



When an apple is punctured by the harmful bug, a drop of fluid 

 exudes from the puncture and gradually increases in size, the cells 

 surrounding it are all killed and a corky layer is formed. To investigate 

 this phenomenon further a number of slices of potato were put in damp 

 chambers (Petri dishes lined with wet filter paper) and harmful and 

 harmless bugs introduced. 



Ann. Biol, vn 4 



