824 I'EOCEEDINGS OF THE THIRD ENTOMOLOGICAL MEETING 



I took 100 healthy worms. of the third stage and injected pebrine 

 spores with a hypodermic syringe. About 70 worms died of wounds but 

 six worms showed a very small number of pebrine spores. In another 

 lot 100 healthy worms of the same consignment were reared for control 

 of which two only were attacked with pebrine. I repeated the above 

 experiment with 100 worms. Eighty-nine of them died of wounds but 

 I could not find a single pebrinized worm out of the eleven surviving 

 ones on the fifth day after injection. The failure of contagion in this 

 case is perhaps due to the following causes : — (1) At the time of inocula- 

 tion blood comes out of the wound and does not allow the pebrine cor- 

 puscles to penetrate inside. (2) The lymph cells of the worms could also 

 eat the spores and thus the worms got rid of the corpuscles. (3) When 

 worms get the infection through wounds, their tissues and muscles are 

 attacked and then the ovaries. 



Regarding the development of the reproductive organs, P. Yieil 

 in his book on Sericulture, pp. 109-110, says : — 



" Les tissus hypodermiques et adipeux, les trachees, les muscles, 

 vont se desogreger et former une sorte de bouillie composee d'une infinite 

 de cellules qui se rapproche de la substance vitelline de I'ceuf 



Aux depens de cette bouillie,' d'autres muscles, d'autres teguments, 

 de nouvelles trachees vont se former et les organes reproducteurs vont 

 s'accroitre." 



If the reproductive organ and not the mid-gut is attacked through 

 wounds the new method fails to eliminate the hereditary infection of 

 pebrine corpuscles. 



Summary of conclusions. 

 From what has been said above we come to following conclusions: — 



1. Infection can take i^lace in three possible ways, 



(1) By heredity, 



(2) By eating the pebrine spores with leaves, 



(3) By infection through wounds. 



2. It is possible that by proper care the progeny of a pebrinized 

 mother, whose ovaries have been infested with pebrine, may be cured 

 of the disease ; but there is always risk of breeding from a diseased stock. 



3. In almost all cases of early infection the spores are so abundant 

 in the moth that they can easily be detected by the Pasteur method. 



4. If infection takes place through food on the day of spinning (after 

 that the worms cannot be infected through food) the organism gets at 

 least 15 days' time to multiply, which time is sufficient for the multi- 

 plication of the spores provided the surrounding conditions are favour- 



