May IS, 191S Wilt of Gipsy-Moth Caterpillars 127 



(23) Minute dancing granules were observed in the Berkefeld filtrate. 

 These may be identical with certain granules observed in smears and 

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



(24) The incubation period of wilt varies, and temperature at times 

 seems to bear an important relation to this variation. 



(25) A large number of caterpillars used in the experiments died of 

 disturbances in their normal physiological activities. 



(26) The success of wilt infection experiments is absolutely dependent 

 upon attention to seemingly insignificant details. 



(27) Genetic immunity of certain individuals is probable. 



(28) Active immunization with sublethal doses is possible. 



(29) The polyhedral bodies may be stages of the filterable virus, but 

 as yet no evidence to substantiate this view has been produced. 



(30) Infection naturally takes place through the mouth by means of the 

 food. 



(31) Some of the imported parasites may be important factors in 

 aiding the dispersion of the wilt disease. 



(32) Although probable, there is no definite evidence as yet that wilt is 

 transmitted from one generation to another. 



LITERATURE CITED 



(i) BoLLE, Johann. 



1908. Studien iiber die Gelbsucht der Seidenraupen. In Ber. K. K. Landw.- 

 Chem. Vers. Stat. Gorz, 1907, p. i. See also Ztschr. Landv/. Versuchsw. 

 Oesterr., Jahrg. 11, Heft 3, p. 279. 



(2) Cu^NOT, L. 



1891. :6tudes sur la sang et les glandes lymphatiques dans la serie animale. 

 Pt. 2. — Invertebres. In Arch. Zool. Exp. Gen., s. 2, t. 9, p. 13-90, 



365-475. 593-670. Pl- 1-4. 15-18, 23. 

 Bibliographie, p. 664-670. 



(3) ESCHERICH, K. 



1913. Neues iiber Polyederkrankheiten. In Naturw. Ztschr. Forst- u. Landw., 

 Jahrg. II, Heft 2, p. 86-97, i fig. 



(4) and MiYAjiMA, M. 



1911. Studien liber die Wipfelkrankheit der Nonne. In Natiirw. Ztschr. 



Forst- u. Landw., Jahrg. 9, Heft 9, p. 381-402, 6 fig. 

 Verzeichniss der zitiertcn Literatur, p. 401-402. 



(5) Forbes, S. A. 



1886. Studies on the contagious diseases of insects. — I. In Bui. 111. State Lab. 

 Nat. Hist., V. 2, p. 257-321, I pi. 



(6) Glaser, R. W., and Chapman, J. W. 



1912. Studieson the wilt disease, or " flacheria " of the gipsy moth. In Science, 



n. s. V. 36, no. 920, p. 219-224. 



(7) 



1913. The wilt disease of gipsy moth caterpillars. In Jour. Econ. Ent., v. 6, 



no. 6, p. 479-488. 



Bibliography, p. 487-488. 

 (8) Graber, V. 



1871. Tiber die Blutkorperchen der Insekten. In Sitzber. K. Akad. Wiss. 

 [Vienna], Math. Naturw. CI., Bd. 64, Abt. i, Heft 1/2, p. 9-44. i pl- 



