66 REPORT ON THE DISEASES OF SILKWORMS IN INDIA 



Causal history of the disease. According to Pasteur there 

 were four organisms to be distinguished in cases of flacherie. These 

 are now classified by most French workers into two groups 

 (Maillot et Lambert, 1906), " Ferment en chapelets de grains " and 

 " vibrions." These may be more simply referred to as a strepto- 

 coccus (S. hombycis) and a bacillus. The first is said to be an 

 organism causing fermentation and the second one causing putre-- 

 faction. Pasteur's idea was that, owing to certain more or less- 

 ill-defined causes, the food in the gut of a caterpillar was not pro- 

 perly digested, and the fermentation organisms which were present 

 on the leaves multiplied and gave rise to flacherie. The disease 

 could also be brought about by feeding caterpillars on the juices 

 from bodies of diseased caterpillars. Further, worms that were 

 produced from a rearing that had suffered from flacherie were 

 believed to have an hereditary tendency to flacherie. Such are 

 still the beliefs of the French school- — the disease is highly con- 

 tagious, it is caused by the organisms described by Pasteur and 

 -it is more or less heritable. 



The Italian school, as I understand it, while admitting the 

 presence of the bacteria, do not attribute the disease to their action. 

 The disease is caused by some disturbance of the caterpillar's meta- 

 bolism, and the bacteria flourish in the favourable medium supplied 

 by the already diseased gut — they are a consequence of the 

 disease, not a cause. The disease is not strictly speaking,, 

 according to this view, contagious or heritable. 



Several Japanese workers have worked on flacherie and, as far 

 as one can judge, their findings point to several bacteria being im- 

 plicated in the charge of causing flacherie — " flacherie is caused 

 not by any special bacterium but by several which occur commonly 

 on mulberry leaves " (Sawamura, 1905). But' of all the bacteria 

 they deal with the most deadly is what they call the " Sotto. 

 bacillus " or the " sudden death " bacillus — identified by them as 

 Bacillus megaterium De Bary, or a variety of this species, indeed 

 Aoki and Chigasaki (1916) distinguished Bacillus sotto as a distinct 

 species having definite cultural characters and especially agglutina- 

 tion reactions. The pathogenicity of this bacillus for silkworms is 

 shown in many experiments, but the peculiar thing about it is that 

 young cultures or broth cultures of the organism did not harm 

 silkworms much under normal conditions — it was only old cultures 

 on agar that caused sudden death. 



The Japanese workers have isolated numerous other bacteria 

 from mulberry silkworms or from mulberry leaves, including 

 Streptococcus hombycis and Streptococcus pastorianus (Sawamura, 

 1902-03), but those were found not to be pathogenic under ordi- 



