PROCEEDINGS OF THE THIRD ENTOMOLOGICAL MEETING 809 



E-^IE II^T MIECD CF ELIMINATING PEBRINE FROM 

 THE ML'LTIVOLTINE SIIKWOEM EACES OF INDIA. 



By M. N. DEj SericuUiiral Assistant, Pusa. 



(Plate 129.) 



Introduction. 



PebBne is a disease caused by a species of s^orozoa. It is a terrible 

 disease in silkworms. Almost all the domesticated species and varieties 

 of silkworms are attacked with it. The wild silkworm races are generally 

 more immune to this disease than the domesticated ones. It threatened 

 the existence of sericulture in Southern Europe in 1865. A crowd 

 of French and Italian savants began to investigate the inexplicable 

 disease but no one was able to find out the true cause of it and suggest 

 any remedial measures. " Uncertainty was not less great when the 

 disease came to be studied. M. de Quatrefages, after a careful study, 

 had believed to be able to characterize it, through the existence in the 

 interior, but chiefly on the surface of the skin of the worms, of small 

 spots, resembling sprinkling of black pepper and thus had given it the 

 name ' Pebrine.' But experience showed that worms might have these 

 spots without having the disease. By continuing, the study of the 

 disease contiadictory results began to appear. Thus Messrs. Lebert 

 and Frey had estabh.'hed that in the interior of all the worms and 

 moths stricken with the disease, was a parasite visible only through a 

 microscope, the corpuscle observed first by M. Guerin Meneville, and of 

 which M. CornaHa has shown the pathological importance. But accord- 

 ing to M. Filiijpi these corpuscles existed normally in all butterflies." 



A real progress, however, was made when M. Osino discovered the 

 corpuscles in the eggs of silkworms and when M. Vittadini had discovered 

 that their number increased in the eggs when the period of their hatchino- 

 approached. The means of selection so far obtained too often gave 

 from " good grain "" bad results. Very often seed would be condemned 

 on uncertain grounds and rearers could not be blamed for not accepting 

 the advice of science. This was the situation in 1865, .when M. Pasteur, 

 at the instance of M. Dumas, began his researches. Next to nothint^ 

 was known of the nature and cause of the disease and efiorts to struggle 

 . against it had remained fruitless. 



The researches of M. Pasteur have entirely elucidated the problem 

 of the existmg malady and led to a practical means sure to arrest it and 

 prevent its return. He clearly pointed out the cause of pebrine and its 

 remedy. Cellular seed and microscopic examination of each mother xte Pasteur 

 moth. I.e., the isolation of each mother in a separate cellule and method. 



