10 REPORT ON THE DISEASES OF SILKWORMS IN INDIA 



twelve years, becoming each year more destructive and causing 

 fears of a total collapse of the trade." Finally, in the section on 

 pebrine in Lefroy's " Report on an inquiry into the silk industry 

 in India " it is actually stated that " this disease appeared in Bengal 

 about 1895 and probably in Mysore between 1890 and 1900." The 

 date 1895 is obviously a misprint for 1875 but what of the state- 

 ment regarding Mysore ? Later in the same section Mr. Hutchinson 

 writes, " in all probability the comparatively small part which 

 pebrine has played in depressing the successful rearing of silkworms 

 in India up to the present time is merely due to the comparatively 

 short time which has elapsed since the introduction • of infection 

 and that, in the absence of effective measures for dealing with it, 

 its future spread and expansion to dimensions similar to those 

 attained in France in the middle of last century is only a matter 

 of time" — a clear expression of the opinion that pebrine in India 

 is a very new disease. In the light of such views it is necessary to- 

 try to determine if pebrine is really a thing of recent introduction 

 into India. 



■s/The fact that pebrine was not recognized as a definite disease in 

 Bengal prior to about 1875 is not to be wondered at, for it was not 

 really properly recognized anywhere until the researches of Pasteur 

 (1865-1870) gave a certain method of diagnosis — that is to say, the 

 examination under the microscope of a portion of the body of the 

 moth selected for seed production and the recognition of the presence 

 or absence of the spores of Nosema bombycis. It is true that the 

 spores had been seen some fifteen years earlier, and that Italian 

 workers had paid some little attention to them in connection with 

 their investigations into silkworm diseasesj^but it was Pasteur who 

 demonstrated conclusively the connection between pebrine and the 

 "corpuscles" — that is to say, the parasitic nature, of the," cor- 

 puscles" — and showed how these could be used as a means of 

 diagnosing the disease?^ But although it was not until about 1870 

 that the technique for diagnosing pebrine with certainty was evolved, 

 there are numerous indications in the earlier writings on sericulture 

 that this disease was no new plague. In the treatise on sericulture 

 by Olivier de Serres, to which I have already referred, and which 

 was published in 1599, there is very good evidence that a disease 

 characterized in part by the presence of spots on the skin was in 

 existence in those days. It was confused with grasserie, it is true, 

 but as pebrine is the only known disease of silkworms that charac- 

 teristically shows this spotting of the skin, it is practically certain 

 that we are here dealing with this disease as well as with grasserie. 

 Later works, such as those of Boissier de Sauvages (1763) and 

 Dandolo (1818), give descriptions of various diseases in which spots 

 on the skin are cited as symptoms. It may therefore be fairly 



