Fancies and superstitions. 157 
where there are markings, these are rather extraneous 
to it than mixed with it. The elegant blue that distin- 
guishes the eggs of the firetail and the hedge-sparrow, 
though corroded away, is not destroyed by the muriatic 
acid. The blue calcareous coating of the thrush’s egg 
is consumed ; but the dark spots, like the markings 
upon the eggs of the yellow-hammer, house-sparrow, 
magpie, &c., still preserve their stations on the film, 
though loosened and rendered mucilaginous by this 
rough process. Though this calcareous matter is partly 
taken up during incubation, the markings upon these 
eggs remain little injured, even to the last, and are 
almost as strongly defined as when the eggs are first 
laid. These circumstances seem to imply, that the 
coloring matter on the shells of eggs does not contribute 
to the various hues of the plumage ; but, it is reasonable 
to conclude, are designed to answer some particular 
object, not obvious to us : for though the marks are so 
variable, yet the shadings and spottings-of one species 
never wander so as to become exactly figured like those 
of another family, but preserve, year after year, a cer- 
tain characteristic figuring. Few animal substances, in 
a recent states contain more hepatic gas than an egg- 
shell, as is manifest from the very offensive smell that 
proceeds from it when burned. A little of this is caused 
by the gluten that cements the calcareous matter, but 
the overpowering fetor comes from the inner membrane 
that lines the shell. 
The superstitions and fancies of persons, though we 
may often contemn them, are yet at times deserving of 
notice, being occasionally to be traced to some former 
received belief or national custom, and perhaps when 
charactered by emblems or ceremonies may be consid- 
ered as certainly originating from the tenets of some 
sect or popular observance ; the partiality manifested 
by the English in general for flowers and horticultural 
pursuits is recently, from a sentence in Pliny (Nat. 
Hist. XIV. chap. 4), supposed to have been acquired 
from their Roman conquerors ; and probably many other 
attachments and practices, though obscured and per- 
verted by time, have been retained from the example 
