Silkworm from Japan. — 423 
value of the Yamamai cocoon only at 4—5 francs, the return 
then would be annually 1,200 to 1,500 franes the hectare,* and 
this with little trouble, and from a material hitherto useless, oak 
leaves. The annual expense would be small: a preliminary hoe- 
ing to clear the ground; a net to cover the trees, which would last 
ten years, and its annual value would therefore be one-tenth its 
cost; the cost of an overlooker for fifty or sixty days, one to 
every two hectares; lastly, the labour attending the crop. Asa 
set-off, on the other hand, we have the annual value of the wood 
cut down at the fall at the expiration of several years, 
So successful was Mons. Personnat in 1865, that on the 27th 
of June he wrote from Laval as follows :}—‘ I have this year 
reared 20,000 oak-silkworms, partly in the open air on 3,000 oak 
shrubs planted last winter, partly in an open room or on cut 
boughs placed in the open air. Success has equally attended all 
three methods. Half my brood are in cocoon, the rest ready to 
spin, all will be finished in another eight days. My worms and 
cocoons are larger than those of last year. I can perceive no 
difference between those reared in a room and those reared in the 
open air from their birth, or placed out after the second 
change; all have done well. My eggs this year remained at the 
natural temperature up to the 12th April without hatching out, 
at which date the oaks were bursting into leaf. It seems to me 
to be possible to recognize in the nearly full grown larval state 
the male and female worms. I have observed that at the fourth 
moult a certain number prepare for the change altogether, some 
days in advance of the others ; these continue to feed up and grow 
more quickly than the others. These then are the first to spin 
and are probably males; the females, requiring a greater amount 
of food, require also more time, and spin their cocoons at a later 
date; hence the male moths appear first. Hence we may be 
able to retard the male larva by affording a smaller supply of 
food and a cooler temperature, so as to get him to spin at the 
same time as the female.” 
This account is very interesting, as tending to show the con- 
tinued success which has attended the cultivation of this valuable 
race in Europe; nevertheless the failures bave been also nume- 
rous; and before concluding I will relate one that occurred in 
1865 to Mons. Claron of Limoux, with eggs that had been re- 
ceived direct from Japan, and sent to him by Mons. Guérin-Mé- 
neville. 
* From £48 to £60. From £19 to £24 per acre. 
+ Revue de Sériciculture, 1865, p. 110. 
