410 Dr. Wallace on the Oak feeding 
them on a polished surface. The experiences of successive 
years tend to show that though eggs sent over from Japan may 
hatch out early in the spring, yet that eggs of the race acclimatized 
in France evince a disposition to wait till the natural bursting into 
leaf of the tree; the oak trees require twenty days forcing in pots 
to put out their leaves, the 15th of March is a convenient time to 
begin forcing. When the time arrives for hatching out the eggs,* 
i. e., when the first buds on the trees abroad begin to break, for 
two or three days together a few worms will emerge in early 
morning; the rest should then be removed by degrees into a 
warmer temperature, about 60°, leaving them for two or three days 
in an intermediate temperature, in order to avoid a too rapid 
change. It is desirable to place the eggs in a little saucer or box 
lid on the tree or on a fresh bough with the ends dipped in water, so 
fastened that the young worms on emerging may at once crawl up 
on to the leaves, as ina state of nature. This process, where there 
are many eggs, requires some modification. His excellency Mar- 
shal Vaillant placed branches in litle bundles, having their ends 
surrounded with moist sponge; this was covered with paper and 
wrapped round with string: this mode enabled him to place the 
boughs in their natural horizontal position, resting on the eggs, 
so receiving the worms naturally. Or, instead of sponge, the 
oak sprays might, when cut, be thrust into a potato, which, by its 
moisture, would suffice to keep them fresh ; too many larvee must 
not be placed on one tree, as it is not easy to remove them without 
damaging them. It is better therefore to hang a number of little 
saucers of cardboard or box lids, each containing the requisite 
number of eggs, over the trees, than to put all the eggs in one 
saucer. If kept in a room it will be found that the worms make 
for the light in their wanderings. Every day the eggs must be 
moistened, to soften the shell and give an easier exit to the larve ; 
this may be done by throwing drops of water over them, and 
moving them about, or by placing them on bibulous paper (which 
may be obtained at any chemists) and moistening the paper. All 
saucers or receptacles for eggs should have holes pierced at the 
bottom to allow the escape of the surplus water, the water retained 
by the gum covering the shell helps to soften it. It is of the 
* Mons. Guérin-Méneville gives the first week in May as a convenient 
time. Revue de Sériciculture, 1863, p.37. He there says that the eggs should 
first be placed at the entrance to a dry cellar, in a temperature not lower than 
35°—40°, not higher than 45°—50°; in a week they may be placed in a warmer 
temperature, say 50°—60°, and later on the temperature may be gradually raised 
to 70°. 
