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, 

 where 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 nights 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 be 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 



