A. S. HoiiNK AND H. M. Lefroy 



:3Si 



leaves are partly severed, so that the leaf or leaflet soon withers and 

 dies. In severe cases the young shoot dies. 



The discoloration of the veins caused by Capsids occurs rapidly 

 after the infestation and discoloured veins are associated with the 

 presence of lacerated pits or areas. Discoloured veins due to Aphis 

 develop after several days have elapsed since the infestation and they 

 are not associated with lacerated tissue. 



The difference in symptoms produced by the Capsid and Jassid is 

 accounted for by different structure of the stylets of the mouthparts. 

 P. R. Awati (Proc. Zool. Soc. 1914, p. 685) figures the mouthparts of 

 Lygus and shows that the outer pair of stylets (the mandibles) are 

 barbed; when they are withdrawn the plant tissue is lacerated. In 

 the case of Ewpteryx, the outer stylets are smooth and they can be with- 

 drawn without further injury than that caused by the sucking. 



The mechanism in Aleurodes is described in another paper above by 

 Hargreaves, but further work is required to compare the action on the 

 plant-tissue of the sucking mechanisms of Lygus, Eupteryx, RJiopa 

 losiphum, and Aleurodes respectively. The actual structure of the 

 mechanism is not sufficient; we are ignorant of the action inside the 

 plant. 



Field observations. 



We are enabled to report upon insect injuries to potato foliage at 

 the following places : 



1. Barley (Herts). 



2. Brentford. 



3. Chelsea. 



4. Dunbar. 



5. Edinburgh. 



6. East Lothian, 



7. Midhurst (Kent). 



8. Oxshott. 



9. Reading. 



10. Strawberry Hill. 



11. Walton-on-Thames. 



12. Wisley. 



13. Woking. 



14. Wye (Kent). 



Potato breeding experiments by Dr Red- 



cUffe N. Salaman. 

 Private garden. 



Experimental plots at the Physic Garden. 

 Field crop. 

 Field crop. 

 Field crop. 

 From specimen. 

 Private garden. 

 Messrs Sutton's trial grounds. 

 Private garden. 

 Market garden. 

 Trial and experimental plots. 

 From specimens. 

 Experimental plots. 



