MICROSCOPIC DRAWING AND ENGRAVING. 
which appertain to it in the perfect state, and becomes the day-fly 
shown in fig. 31. 
44. It now rises upon its wings into its new element, the air, 
w T here it joins tens of thousands of its fellows, who have almost 
simultaneously undergone a similar transformation. In the fine 
afternoons of summer and autumn, swarms of these creatures may 
be seen hovering in the air, all of them having emerged the same 
day from the state of chrysalis. Each female in these flights seeks 
its mate; which having chosen, they retire together to the leaves 
of some neighbouring plants. Immediately after their conjugal 
union, their proceedings are such as would he prompted by the 
tenderest parental solicitude for their future offspring, which, 
however, they are never destined to behold. Conscious, apparently, 
that their young must inhabit a very different element from that 
in which their short existence passes, they fly off in quest of water, 
in which, when found, the provident mother deposits her eggs, 
collected in a little packet in which they can float; the parents 
then abandon them to the warmth of the atmosphere, by which 
they are subsequently hatched, and having thus performed the 
last and most important duty of their life, that of increasing and 
multiplying their species, drop dead, the whole period of the exist¬ 
ence of this gay insect being limited to a few hours of a summer 
afternoon. 
45. So imperious is the will of nature in enforcing her laws, 
that if by artificial interference, the insect after emerging from 
the envelope of the chrysalis be prevented from joining its fellows 
and kept in solitude, its life will be prolonged far beyond its natural 
term, as if it lived only for the performance of the duty prescribed 
to it by its Maker. Dr. Goring ascertained this fact by catching 
a day-fly just emerged from the chrysalis, which he imprisoned for 
several days, during which it continued to live; he observed that 
in such cases the insect did not seem at all enfeebled, even when 
thus confined for a week, so that upon being liberated it flew 
briskly away, found its mate, produced and provided for its eggs, 
and immediately died. 
46. It is remarkable that these little creatures, during their 
ephemeral existence, take no food ; the only function they 
exercise being that of propagation. 
47. It appears, that in some localities, these flies prevail in such 
countless numbers that their bodies are found after death covering 
the ground to a considerable depth, and they are collected in cart 
loads by the agriculturists, who use them for the purpose of 
manure. 
SO 
