CULTURE OF SILKWORMS. \f 



unable to spin properly, for examination, as these feeble indivi- 

 duals are sure to show disease, if present at all in a brood. All 

 those that I examined under the microscope were swarming with 

 jyanhistophyton ovatum, of Lebert, tbe bacterium which causes 

 pelirine, the worst disease to which silkworms are liable, as it 

 is not only infectious but hereditary. This disease could have 

 no sort of connection with the mulberry leaf disease, but must 

 have been imported from China, either in the eggs or by means 

 of infected trays or cocooning frames, which were all brought 

 from China, or it may have been contracted in the way which 

 will be mentioned hereafter. On previous visits that I paid to 

 Ayer Kuning I had been assured by the Chinese that they had 

 had no deaths amongst their worms, but financial reasons may 

 account for their not giving correct information on this point. 



The micro-organism causing the disease is thus described 

 by Mr. E. M. Crookshanh in his Practical Bacteriology. — ''Pan- 

 histophyton ovatum, Lebert {nosema homlycis, micrococcus ovahis, 

 corpuscles (hi ver a sole), shining oval cocci, ^-j^^ to jy^j^ mm. long, 

 Y^ mm. wide, singly and in pairs, or masses ; or rods, ^^ mm. 

 thick and twice as long. They multiply by sub-division. They 

 were experimentally proved to be the cause of pebrine, gattine, 

 maladie des corpuscles, or Jleclisucht ; and were discovered in the 

 organs of diseased silkworms, as well as in the pupae, moths, 

 and eggs." 



I have not detected any of the three other principal silk- 

 worm diseases — grasserie, muscardine and flaccidity — amongst 

 the worms in Perak. 



FAILURE OF THE CULTIVATORS. 



After repeated losses caused by the death of whole broods 

 of worms, and by the much reduced quality of the silk yielded 

 by the silkworms, both the original Chinese cultivators and Mr. 

 Light abandoned the attempt of cultivating them in February 

 of 1892, after having made a fresh importation of eggs from 

 China at the end of 1891. These, however, as they were reared 

 in the same rooms and on the same trays as the old ones, naturally 

 contracted the disease and also died out. 



EXPERIMENTAL BREEDING TO ELIMINATE THE 

 DISEASE. 

 On lOth September, 1891, 1 wrote as follows on this subject : 

 " Having proved the existence of pebrine amongst the worms here, 

 it is a subject for the consideration of Government whether (a) 

 they will take any measures to stamp it out, or (h) let th(^ intro- 

 duction of silk-growing in Perak become a failure, as it most 

 sm-ely will without Government intervention. 



