257 



Grandori (R.). Studi sulla Flaccidezza del Bombice del Gelso. Nota 

 preliminare. [Studies on tlie Wilt Disease of Bottibyx mori.] — 

 Boll. Soc. Zool. Ilaliana, Rome, (4) i, no. 1-2, 31st March 

 1920, pp. 17-28. 



The findings recorded in this preUrainary note are not claimed to 

 provide a sure means of diagnosing the presence of wilt disease in the 

 egg of Bombyx mori, but it is hoped that they justify further work on 

 these Unes. 



Admitting, as a working hypothesis, the presence in certain eggs of 

 B. mori (healthy and uninfected with any germ) of a hereditary 

 predisposition to wilt disease, the author questioned whether careful 

 microscopical examination of the immature egg, the fecundated egg, the 

 yolk and the developing embryo, would not yield a constant 

 morphological character pecuhar to the egg hereditarily predisposed to 

 wilt and visible on comparison with a healthy one. Such a difteren- 

 tiation would be of practical value, even if the specific disease germ 

 remained undiscovered. 



It was found that in healthy moths the yolk of the immature egg 

 consists, at its periphery, of minute granules that increase in size 

 towards the centre, where they are large. These granules are homo- 

 geneous. In diseased examples the largest granules (about equal in 

 •size to the central ones in healthy specimens) are at the periphery, 

 and the size diminishes towards the centre, where it is much smaller 

 than that of the minute peripheral granules in healthy specimens. 

 These large peripheral granules of diseased individuals are not 

 homogeneous, and the very minute central ones are almost unstainable 

 with any of the usual plasmatic stains. 



The choriogenous cells of the ovarian tubes of a diseased moth are 

 in an advanced stage of histolysis, and the structure of one cell is not 

 distinctly defined from those of contiguous ones. In healthy ovarian 

 tubes these cells are defined and recognisable ; and there are other 

 differences also. 



In the case of eggs already deposited, the differences in the yolk 

 are so marked as to be recognisable by a non-expert using a low 

 magnification (125 diameters). In the healthy yolk there is a very 

 thin layer of ectoplasm and a central sphere of cytoplasm surrounding 

 the nucleus or nuclei. In the yolk of an egg from a diseased moth 

 the layer of ectoplasm is present in part only and is sometimes 

 indistinguishable, and the two spheres (yolk and cytoplasm) are 

 confused. The serous membrane of a healthy egg envelops the entire 

 yolk, but in a diseased one the serous membrane sinks into the yolk 

 and is at a certain depth on the third day after oviposition. 



NoMAGucHi (G). Taisho 7-Nen Mikanbai Kenkyu-Jiseki. [Results 

 of Orange Fly Investigation, 1918.] -Oita-Ken Nainmbu [Interior 

 Division Oita Prefedural Government], August 1919, 16 pp., 

 1 plate. 



The investigation here described has been carried out by the author 

 under the supervision of Dr. Miyake at the Orange Fly Research 

 Laboratory at Tsugumi in the Oita Prefecture. The results are, 

 therefore, mainly supplementary to the information given by the latter 



(684) Wt. P1850/163. 1,500. 7.20. B.&F.Ltd. Gp.11/14. ^ 



