72 REPORT ON THE DISEASES OF SILKWORMS IN INDIA 



tion and putrefaction are set up in the gut and the caterpillar 

 rapidly dies. 



The question of the production of toxins by the bacteria which 

 thus multiply is not an easy one to settle. Sawamura (1902-03) 

 was of opinion that no toxin was produced, the damage being 

 caused by such simple products as " ammonia formed by protein 

 decomposition, or of nitrites formed from nitrate contained in the 

 leaves, or of acids produced from the carbohydrates." On the 

 other hand, Aoki and Chigasaki (1916) have shown that B. mega- 

 terium bombycis produces a toxin which is very fatal to silkworms. 

 These two workers found that a six days old agar culture of the 

 bacillus produced under normal circumstances almost instant death. 

 My experience does not agree with theirs, for none of the bacteria 

 which I isolated from diseased worms produced any effect on 

 normal worms under normal conditions even when the cultures 

 fed were 6 days old or more (Experiments 25 and 26). In this 

 my findings are comparable with Sawamura's. It is possible 

 that Aoki and Chigasaki had a particularly virulent strain of 

 B. megaterium. 



I have referred to certain cases of " flacherie " in which bacteria 

 were not demonstrated. Probably some writers would not admit 

 that the term is correctly used — the presence of bacteria being 

 necessary for a correct diagnosis. Personally, I believe that this 

 view — -that of the French workers — is rather extreme, and I would 

 incline more to the view of the Italian sericulturists that the bac- 

 teria are not the exciting cause of the disease but a consequence 

 of an abnormal condition of the gut. This " acid indigestion," 

 as I have called it, may even kill off weakly worms. The symp- 

 toms are the same as those for flacherie — vomiting, diarrhoea, 

 thickening of the peritrophic membrane and brown colour of the 

 gut contents. Discolouration of the body may be noted — the 

 brown gut contents serving to account for this at first. After 

 death, of course, there is multiplication of bacteria in the gut and 

 finally putrefaction accompanied by blackening of the body. 

 Worms showing these symptoms are, I believe, correctly diagnosed 

 as suffering from flacherie even if bacteria cannot be demonstrated. 

 While this is so, it must be admitted that the multiplication of 

 bacteria usually got as consequence of this digestive disturbance is 

 so characteristic a feature of the disease, that the presence of 

 numerous bacteria without any of the ordinary symptoms of 

 flacherie would justify one in condemning the worms or moths as 

 suffering from flacherie — it being taken for granted that this multi- 

 plication of the bacteria is a clear indication of the metabolic dis- 

 turbances which we have called " acid indigestion." 



