216 Dr. Wallace on 
the later stages during harvest; during the middle stages, the 
silkworm being no longer gregarious is scattered uvver the trees, 
and being of moderate size is less conspicuous and likely to 
escape detection. The weight too of the foliage is continually 
increasing up to the end of September, so that the largest ciop of 
cocoons may be obtained by beginning in July, and putting on 
relays of larvee, without actually having two generations, 
For the development of the insect is so very readily accelerated 
or retarded by a higher or lower temperature, that it would be 
perfectly easy to ensure, after a little practice, a succession of 
moths to come out every day in the year, by exposing the cocoon 
to artificial heat or cold. Hence without absolutely having two 
generations, we might allow the trees to obtain considerable vigour 
during May, June and half July, before placing any worms 
thereon; the shoots will then be four feet or more high; then for 
the first three weeks of the life of the insect the trees will grow 
faster than the larvee can consume the leaves; during their third 
stage the larve eat more, and during their last stage, which would 
be the end of August and beginning of September if the eggs 
were laid July Ist to 14th, the trees may be completely stripped. 
A slight growth of young leaves at the top will subsequently take 
place, from six to eight leaves being emitted, sufficient to enable 
the tree to recover from the check which it has received from 
being denuded of foliage. 
For it must not be imagined, as many relate, that the tree 
throws out the more vigorous and Juxuriant growth, in proportion 
as it has been fed down by the larvee. The late Mr. Knight, the 
celebrated horticulturist, laid it down as an axiom in horticulture, 
that the growth of a plant is in proportion to the amount of foliage 
exposed to sunlight; it follows then that of two trees, one being 
fed off by larve, the other untouched, the growth of the latter will 
be far greater than of the former; this is exactly what I have 
observed during the past summer. Where the larve were placed 
so thickly on the trees as to create a complete denudation, the 
growth for the year, though luxuriant, was not nearly so luxuriant 
as of those where the silkworms were placed on sparingly, while 
trees which had no larvee placed on them grew more luxuriantly 
than either. That the trees do receive a check from having their 
foliage eaten is in accordance with nature and with the result of 
these comparisons, notwithstanding any assertions to the contrary. 
It follows then that as our object is to attain each year the greatest 
amount of luxuriance of foliage to be consumed as food by silk- 
worms and transmuted into silk, we must so manage as to give 
the least possible check to the growth of the tree. If now we 
