INSTITUTE, PUSA, FOR 1917-18 131 



to the factory equipment at the beginning of the current 

 year; this consisted of a masonry vat sunk in the ground 

 and having sloping ends and a draining platform. The 

 water in the vat is heated with steam and the hot extract 

 can be pumped to the steeping vats for cooling and inocu- 

 lation. Plant is carried -into and out of the vat by a length 

 of large mesh wire fencing net, thus obviating the trouble 

 in handling hot material. 



The experiments made with this method do not come 

 within the scope of this year's report^ but it may be said 

 here that there appears good reason to suppose from results 

 already obtained, that the method will allow not only of a 

 high percentage of extraction, but of complete bacterial 

 hydrolysis and the production of good quality indigo. It 

 is, of course, quite possible that its use on a factory scale 

 may prove uneconomical in view of the fuel consumption 

 involved, but engineers whose opinion has been taken do 

 not consider that this is likely to be the case. 



V. Pebrine. 



Further work was done upon this subject with special 

 reference to the mechanism of infection, a paper on which 

 is now in hand. Microtome preparations and dissection 

 gave clear evidence of the rapid rate of development and 

 spread of the parasite in the tissues of the host in this coun- 

 try as compared with that described by Pasteur ; thus artifi- 

 cial infection of a larva, by feeding only once with pebrme- 

 infected food just before spinning, resulted in a heavily 

 pebrinized moth, and in earlier stage larvae similar treat- 

 ment resulted in the presence of numerous actively dividing 

 forms of the parasite in the epithelial cells of the gut of 

 the host only three days after infection, as compared with 

 a necessary interval of ten or fourteen days in France. 

 Similarly in hereditary infection through the egg the 

 epithelial cells of the gut of the embryo were found to be 

 infected several days before oviposition. It is therefore 

 clear that Nosema bombycis in India has attained parasitic 



