Kenneth M. Smith 45 



a pure culture of a bright chrome-red organism was obtained. A number 

 of the harmless apple-feeding Capsids in a starved condition were 

 then introduced into a petri dish containing the above culture; after 

 they had all been observed to insert their stylets into the medium and 

 to be well plastered with the colonies, they were transferred to a fresh 

 young apple shoot and allowed to feed, no damage resulted. Suspensions 

 were then made of the colonies and injected by means of a sterile syringe 

 as follows into both apple and willow leaves: 



(1) Sterile water control. 



(2) Suspension of living bacteria. 



(3) Suspension of dead bacteria (boiled). 



A larger area of damage was caused by (2) and (3) than by the 

 control, there presumably being a toxin present due to the presence of 

 the bacteria in the injection, but as the damage caused by (3) was 



Mx.St. 



Fig. 3. Mandibles and maxillae of Lygus pabulinus. Drawn with the camera lucida, under 

 the T V oil immersion, ocular 4. 



precisely similar to that caused by (2), it cannot be taken as evidence 

 that bacteria are the cause of the injury under investigation. 



Inoculations were then made with a number of common bacterial 

 saprophytes, including the red organism already mentioned, in order 

 to find out if any of them would continue to live saprophytically in 

 the plant tissue if entrance were made for them, either artificially by 

 the needle or by the Capsid's stylets, and if so, whether they would pro- 

 duce damage similar to that known to follow the feeding of P. rugicollis. 



The following inoculations were made into apple leaf: 



(1) Suspensions of the red bacteria isolated from the damaged apple 

 leaf. 



(2) The same with dead bacteria. 



(3) Suspension of Bacillus mesentericus. 



(4) Suspension as in (3) but boiled. 



