CULTUKE OP SILKWORMS. 11 



healthy condition, by strict isolation and by submitting it to 

 microscopic or other selection in the manner hereafter explained. 



PEBEINE AFFECTING WILD MOTHS IN PERAK. 



His Excellency the Grovernor some time back sent me, 

 through the Acting British Resident, a num^ber of the reports of 

 the Indian Silk Committee, and in one of these papers it was in- 

 incidentally mentioned that pebrine, the disease which has been 

 causing snch havoc in Perak, affects other genera of the lepidop- 

 tera besides the genus to which the silkworms belong, and it 

 occurred to me that an examination of the wild moths might 

 be useful. With this object I began a microscopical enquiry, 

 and on the evening of the 1st February found a common wild 

 moth badly affected by pebrine. The bacteria were identical 

 in form, size and refringeuce with those from the sillrsvorms, 

 with which they were carefully compared, and there appears no 

 reasonable cause to lead to the supposition that they are not 

 the same micro-organism, though the actual proof — viz., inocula- 

 tion — is wanting, and rather hard to apply, with any hope of 

 obtaining positive results. 



This unlooked for and disagreeable discovery clearly indi- 

 cates that the disease is endemic in Perak, and that, although it 

 may be eradicated from all the silkworms in the State, or a 

 perfectly pm'e breed be introduced, yet they will always be subject 

 to re-infection from coming into contact with wild i:>ebrinous 

 lepidoptera, or the virus emanating from these diseased insects. 



It was pre\aously concluded that, owing to the isolated posi- 

 tion occupied by Perak in regard to silk culture, infection was 

 only to be feared from outside, and that, given a healthy breed of 

 worms and proper precautions against the introduction of disease 

 from China or India, that the worms would enjoy comj)lete 

 immunity from pebrine. This hj^j^othesis is now apparently 

 shown to be fallacioiis, and, instead of once eradicating the 

 disease, it will be necessary to piirsne a continuous course of 

 selection of seed, if the cultivation is ever to be carried on suc- 

 cessfully. 



CONDITIONS NECESSARY TO ENSURE SUCCESS. 



As the result of over two years' observation and exjieriment 

 on the growth of silkworms in Perak, I have arrived at the 

 following conclusions. 



The houses used to rear the worms in should be small and 

 detached from one another. They should not be too high, and be 

 made fairly light. They should be used for only this one ])ur- 

 pose and should not be used as dwelling-houses, nor stables, nor 



