14 
Cin.TUBE or SILKWORMS. 
seiof't ion (tf firsts,*' tliey would jiekl, say» 240,0(^0 c^^jrs,* or 
1^0,000 female ** seconds'/' wbit-li ti^o^m would yield 24 iiiillious 
of eggs for distribution. This numrier of worms would ^ive 
1<5'458 fcous of '* green" eocoous, or at four broods per ajiuiim» 
siiy 64 tons, as the outcome of the work of a siugle mieroseujijgt 
for a yejtr. Tliis is as much as a hundred iiiicr<tseo]>ists couJd 
do, with multivoltinc woruis, if working by the ordixiaxy method 
of sekction as practised tu Eurojie. 
The whole system depends on gtmrding from exttTual 
sources of eonta*^itm the j^neratiou after that whieh has been 
ja'oved to be free from disease lij niicroseopieal examluation. 
To do this, clcanliuesB, tlie free use of antiseptics, isohitiou, and 
the throwing of the food in a jtlaee where it will not Ik} infected 
by unhealthy wonos^ are the main poiots to he attended to. As 
a precautionary measure, the firsts " might be divided advan- 
tagwnsly, and kept in two separate houses. 
Prom time to time it mit^ht be necessaiy to introduce fresh 
blood into the breed, and for this purpose the fresh wonua 
shoidd Ix; microscopical ly selected for four or five generations 
Ixyfore mixing them with the original firsts," being kept 
during their probation in a house iaolatLKi from all the otliers. 
It may he mentioned here that I have fouud that a single selec- 
tion, never mind how carefully it is done, is insufficient to elim- 
inatc pebrine from a race of worms. Therefore it follows that 
it is useless to attempt to produce " seconds " until the " firsts " 
have been thoroughly purged of all traces of disease, by 
repeated selections. 
In an estaliHshment such as is here suggested, the micro- 
scopifit would he the only highly paid man. AJi the other work 
civuld lie done, after a little time, by ordhiary eooUes, so that 
the cost of maintenance would be comparatively unimportant, 
and the eggs eonld be sujiplied at a low price. 
I venture to think that this system, if earrieJ out proj>er!y, 
will do for the multivoltine silkworms of the troj-tics what the 
system practised in Europe has done for the annual silkworms 
of temperate climat^}s. 
SELECTION BY LOIfOEVITT. 
Mr. B. Blechynden communicated to me a plan he has been 
trying, to effect the selection of healthy worms for breeding 
• A fejTialu Jiomh^se /sinensis T laid lays oii ati avemjii; 355 eggs, 
wolgliiiifj 2414 f^^niim; 100 moths vvoultl liij diit* (Hiiiee of cjigs, thu rttiiinJard 
ounce lieiug 15 gnvuiK ur 38.5'8 ffKiins. In the ubore ostimates it has been 
uE«amed that cucli moth will produce vn\y 2QU woiiog. 
