JJo, 3. ] Silkworms hi India. 133 



suitable ; in Bengal Morns indtca is the mulberry generally used for silk- 

 rearing 1 . 



The mulberry silkworms of the temperate zone have long been 

 known to suffer from a number of diseases. These were studied 

 exhaustively by Pasteur, between the years 1865 and 1870, and the 

 remedial measures which he recommended have since been widely adopted 

 in Europe, where they have proved the salvation of the silk industry. In 

 Bengal, mulberry silkworms suffer from similar diseases, which have 

 been fouud by Wood-Mason and Mukharji to be identical with the 

 diseases known in Europe. Within the last few years accordingly 

 experiments have been carried on in Berhampore, with the support 

 of the Government, with a view to introducing Pasteur's system into 

 India. Baboo Mukharji, who conducted the investigation, has found 

 some practical difficulties in the way of applying, to the multi vol tine 

 insects of Bengal, the remedies that were devised for the univoltine silk- 

 worms of Europe; there would seem however to be considerable reason 

 to hope that Pasteur's methods may ultimately be adapted to the require- 

 ments of the Bengal silk industry. 



A detailed account of the chief diseases to which domesticated mul- 

 berry silkworms are subject is given in the special part of this paper which 

 deals with Bombyx mori proper, p. 142. The following is a summary : — 



a. Pebrine*, which is known in Bengal as katd, or, when in an 

 aggravated form, as tali, is characterized by the presence of microscopic 

 corpuscles 3 of oval shape which are found in the tissues of the silk- 

 worm, and also in the pupa, moth and eggs. The disease is not always 

 fatal, but when it does not kill the worm it damages the quality of the 



which time they hatched out healthily when incubated by increasing the temperature. 145 

 days he considers to be about the minimum time required for the healthy hatching of eggs. 

 He observes that the hatching can he retarded, so as to make the eggs take up to twenty . 

 months in producing caterpillars, by keeping them at a uniform temperature of about 60° 

 to 70° Fahrenheit, from the time they are laid through a series of months, after which 

 they can be hatched out healthily by refrigeration and gradual warming as before; 

 about three months in all being taken up by these processes. 



1 See Notes by Duthie and Blechynden in the Journ., Agri.-Horti. Soc, Vol. VI (1878 

 to 1881). 



8 Mukharji reported in January 1888 that, while Flacherie, Orasserie, and Muscardine 

 have always been known in Bengal, Pebrine has only appeared within the last ten or twelve 

 years, becoming each year more destructive, and causing fears of a total collapse of the 

 silk trade. 



8 These are the corpuscles of Panhistophyton ovatum (Nosema bombycis, Micrococcus 

 ovatus, corpuscles du ver a soie), shining oval cocci 2 — 3 ft. long, 2 fJ-. wide, occurring 

 singly and in pairs, or masses, or in rods 2"5 fJ.. thick and 5 //. long. They multiply by 

 subdivision. They have been experimentally proved to be the cause of pebrine, gattine, 

 maladie des corpuscles, or fleck &ucJit ; and are found in the organs of diseased silkworms, 

 as well as in the pupse, moths and eggs. — (Crookshauk's Introduction to Practical Bacte- 

 riology i London, 1886). 



