REPORT ON THE DISEASES OF SILKWORMS IN INDIA 81 



It is, however, only the rot diseases that cause really serious 

 loss to the muga rearer. I was fortunate enough to be able 

 to study an outbreak of flacherie which occurred in the neighbour- 

 hood of Titabar in March 1921. The external symptoms were 

 typical. The bright green colour of the worm became dulled and 

 it gradually ceased to feed. The faeces were semi-liquid and many 

 worms were vomiting a brown, clear vomit. The body became 

 very flabby and death ensued. The worms just before death and 

 for some little time afterwards hang downwards from the twigs 

 attached to them by the anal prolegs, gradually turning quite 

 black and sooner or later dropping to the ground, all the organs 

 and tissues dissolved into a putrid black fluid. When the gut of 

 recently attacked caterpillars was examined it was found to con- 

 tain undigested leaf, or very often a brown, soft, somewhat jelly- 

 like substance. The peritrophic membrane was thickened and 

 somewhat opaque. As a rule the blood in these caterpillars was 

 rather scanty in amount. Strangely enough, bacteria were not 

 found in any numbers under the microscope except when the worm 

 had been some time dead and decomposition had set in. On cul- 

 tivating gut contents, however, numerous colonies of Bacillus A 

 and Micrococcus a were got with a very few colonies of Micro- 

 coccus b. In smears made from the gut of still living worms a 

 email number of micrococci were seen and a very few bacilli. 



The two chief bacteria isolated from this outbreak of disease 

 were fed to seven different lots of muga worms on three different 

 occasions (Experiment 29). The results were very confusing. 

 In the first place the controls all showed a certain amount of 

 disease, the symptoms being those of flacherie, and in most of these 

 cases bacteria were got in the gut. The muga worms used in these 

 experiments were all reared inside the laboratory on branches of 

 " mezankuri " (Litsea citrata) placed in bottles of water with 

 cotton wool stuffed into the neck of the bottle round the stem 

 to prevent the worms from leaving the branches. For worms 

 accustomed to an open life the conditions were not ideal, and it 

 is surprising that they were as healthy as they turned out to be- 

 The method of rearing was doubtless responsible for the disease 

 among the controls. The gut of a muga worm feeding normally 

 in the open is strongly alkaline (pH=9*8). The worms which 

 I reared in the laboratory were much less alkaline, showing the 

 same hydrogenion concentration as many of the mulberry worms 

 kept in the hot moist chamber (pH=8"6). Furthermore, the con- 

 trols and the ones that showed obvious symptoms of flacherie were 

 of the same degree of lessened alkalinity. The fed lots then could 

 not be expected to be free from disease ; the point to determine 

 was, were they more diseased than the controls ? On the whole 



