I. 
ROSETTA. 
the river, where we procured two that lived chap. 
with us until we finally left Egypt. They were 
large of their kind, and of a most vivid green 
colour when first taken. Afterwards, their 
common appearance was that of the brown 
lizard ; and we found as they became unhealthy 
that their power of changing colour diminished. 
Indeed, this effect is seldom rapid or instanta- 
neous ; it seems always the result of sudden 
apprehension or surprise, when the poor de- 
fenceless animal, having no means of resistance, 
gradually assumes the colour of some substance 
over which it passes ; being thus provided by 
Nature with the means of concealment. Fross 
and toads appear to possess this property in a 
certain degree, although it may have escaped 
the observation of naturalists : after these 
reptiles have remained a certain time upon a 
recently-turned border of earth, their colour 
so much resembles that of the soil, that they 
are not easily perceived ; and sometimes among 
grass, when alarmed by the sudden approach 
of any other animal, they assume a greenish 
hue. The inclosures for gardens near Rosetta 
are formed by hedges made of palm-branches, 
or of the Cactus Ficus Indica, Prickly Pear : we 
often collected the fine yellow blossoms of this 
plant: they are faithfully represented in tli^ 
account published of Lord Macartnei/s Voyage 
B 2 
