230 Dr. Wallace on. 
trees from eighteen inches to two feet apart each way and some 
only one foot apart ; the soil was good and light, and in 1864, the 
trees made good shoots, many of them five and six feet long; in 
1865 some of the shoots were ten feet long, and the growth was 
so luxuriant as to astonish all that passed by. Early in the 
summer he netted over a portion, intending to place therein the 
young worms, but the luxuriant growth soon escaped from the 
netting, so that that method was abandoned, and the worms placed 
in the Ailanthery without protection. On the 18th of November I 
obtained his report; there were then still leaves on the summit of 
the trees, though in exposed places they had all fallen by the 10th 
November. Out of 1,700 eggs he obtained 458 cocoons ; of these 
120 larvee were fed in-doors, the rest were fed on the trees. 
Robins were observed to be troublesome, and likewise ants. It 
should be borne in mind that, in estimating the number of cocoons 
as obtained from any number of eggs, regard should be paid to the 
proportion of eggs which do not hatch out, and likewise to the loss 
which happens in the first ten days of larval life, before the time 
arrives between the first and second moult, at which generally the 
young larvee are counted and turned out for good, as was done by 
Lady Heathcote in the preceding experiments. I consider that as 
the eggs form a saleable object, and are the first origin of the 
crop, so we should, in estimating our crop, calculate from the 
number of eggs we operate with, rather than from the number of 
young larvee which we place on the trees; for these give no clue 
to the number of eggs necessary to produce them, and therefore 
conceal the expenditure of the starting-point, viz. the number or 
weight of eggs operated upon. 
In 1865 for the first time I commenced to experimentalize on 
a large scale entirely in the open air, having the two preceding 
summers operated ona small scale both out of doors with and with- 
out protection, and also in doors, in order to familiarize myself with 
the habits of the larva, and with some of the difficulties of its culture. 
I had about 600 cocoons to begin with, and about 2,300 Ailanthus 
trees planted in rows, containing from four to six trees in a row, 
along the margin of a railway as before described ; (see p. 212). 
My plantation extended more or less interruptedly for half a 
mile; the soil was a deep tenacious loam, capital corn land. 
My first moth emerged May 22nd, my last July 27th, in all 563 
moths emerged; of these 230 pairs were fertile, and laid in all 
87,000 eggs. My first eggs were laid May 24th, the first larva 
was hatched June 11th: my first cocoon was spun July 15th, an 
interval of thirty-four days from June 11th; from this cocoon 
