Mr. W. Sells on the Silk-Worm. 
41 
with the ends rounded, and some of them rather contracted 
in the middle ; the loose or floss silk is inconsiderable, the 
cocoons are less easily wound off' and do not yield quite so 
much of the material, but the silk is beautifully soft and 
fine in texture. 
August 27. — The moths commenced making their appearance, 
and came out in succession during the following ten days. 
September 14. — The first pair of moths died, and by the 29th 
all of them were extinct, so that the whole average period 
of the insect’s existence, from the hatching of the egg to 
the death of the imago, was one hundred days. 
The business of impregnation in the silk-worm is very slowly 
effected, and requires a repetition of intercourse between the sexes 
to complete the process of fertilizing the whole mass of ova. Se- 
veral pairs of moths were placed separately in trays, and covered 
with gauze to prevent escape, the better to observe the results cor- 
rectly. One pair, which coupled on Wednesday the 7th of Sep- 
tember, were found united on the 16th, having however been 
separated during the ten days more than once, for a short period, 
when the female laid a number of eggs, — on the 17th they parted 
finally ; the male died on the 20th, and the female on the 24th, 
after having deposited 796 eggs. 
In another case the coitus continued 60 hours, when the female 
laid 150 eggs ; she then recoupled, and remained so during two 
days. 
In a third instance the union lasted above 72 hours, when they 
were found apart, but oviposition had not commenced. 
The worm is slightly distinguishable front that of the long do- 
mesticated variety by a blackish spot on each side of the head ; the 
moth is perhaps somewhat larger, and the dark lines on the wings 
rather more deeply coloured. 
It appears very questionable whether this variety of the insect 
could be advantageously cultivated, as the silk is not of quite so 
strong a texture, is less in quantity, and not wound with the same 
facility as that of the common sort ; at the same time it would be 
injudicious to pronounce what might prove to have been a pre- 
mature opinion, as further careful investigation may show that the 
white silk is better adapted to particular purposes in manufacture 
than the orange and the pale yellow sorts are. I would, therefore, 
recommend a further and more extended cultivation of the white 
variety, in order to ascertain if the present apparent objection may 
not in some measure be overcome, and that we do not hastily de- 
spair of its available usefulness. 
