150 jourxal of economic entomology [vol. 9 



Summary of Our Previous Work 



The results obtained by our previous studies may be summarized 

 as follows : 



1. The wilt of gipsy moth caterpillers is a true infectious disease 

 distributed over the entire territory infested by the gipsy moth. 



2. Epidemics of the disease occur only in localities heavily infested 

 by the gipsy moth. 



3. Chmatic conditions appear to bear an important relation to wilt 

 in the field. 



4. The disease is more prevalent among older than among 3'ounger 

 caterpillars, but the latter also die of wilt in the field. 



5. No diagnosis of wilt is valid unless polyhedra are demonstrated 

 microscopically. 



6. There is no record of the occurrence of wilt in the gipsy moth in 

 America prior to 1900. 



7. Minute dancing granules may be observed in wet smears. 



8. Polyhedra are probably reaction bodies belonging to the highly 

 differentiated albumins, the nucleoproteids. 



9. The pathology of wilt does not vary with the age of the cater- 

 pillars. 



10. The poh'hedra originate in the nuclei of the tracheal matrix, 

 hypodermal, fat, and blood cells. 



11. The nuclei of the tracheal matrix and blood cells seem to be the 

 first tissue nuclei affected. 



12. Many minute violently' dancing granules are found in the patho- 

 logical nuclei of fresh tissue. 



13. Giemsa's stain demonstrates many little granules in the nuclei 

 of diseased tissue sections. 



14. The alimentary canal seems to be the last organ in the body 

 to disintegrate. 



15. Two types of blood corpuscles exist in normal h^emolymph. 



16. Two types of pathological blood corpuscles exist in diseased 

 caterpillars. 



17. The blood is a fairly reliable index of a caterpillar's condition. 



18. The blood test is impracticable for large experimental series. 



19. Bacteria are not etiologically related to wilt. 



20. The virus of wilt is filterable with difficulty. 



21. Such a filtrate is free from bacteria and polyhedral bodies. 



22. Caterpillars that have died from infection with filtered \arus are 

 flaccid, completely disintegrated, and full of polyhedra. 



23. Minute dancing granules were observed in the Berkefeld filtrates. 

 These may be identical with certain granules observed in smears and 

 tissue nuclei (sub. 7, 12, and 13) and may be etiologically significant. 



