40 THE AUSTRALIAN NATURALIST. 
Set iaghlpt eal 
highest sense essential to their safety and well-being. If it 
were not for this many species, owing to the vigilance, and 
often superior strength of foes, would become extinct, and so 
the balance in nature would be disturbed. Protective coloura- 
tion and formation may often be linked together, for although 
many of our native spiders are protected by colour merely, 
others complete the disguise by simulating as well the 
shape or form of neighbouring objects, such as broken shells or 
pebbles on our sea beaches, the excreta of birds, or buds and 
twigs in the forest; colouration and formation when they aid 
in shielding an animal, may be summed up in one term—pro- 
tective resemblance. The most usual form of -protective 
resemblance is that of simple concealment. The animal simu- 
lates, more or less exactly, the appearance of some object that 
is of no interest to its enemies, and so passes undetected ; or 
it harmonises in a general way with its surroundings, and so 
succeeds in eluding attention. Protective resemblance is that 
in which an animal imitates an inanimate object ; mimicry, 
on the -other hand, implies that an otherwise defenceless 
animal mimics more or less accurately an animal that by 
some reason is protected from its enemies, or even an animal 
that preys upon its class. 
In the spider world members eat as they are eaten. Some 
of them are active and some sedentary. ‘lo each of these 
classes colour is of vast importance. By its aid the former are 
enabled to stalk prey, undetected, while the latter, when danger 
threatens, may take cover and remain hidden until all is safe. 
The principal of adaptive colouration, though early recognised, 
found no intelligible exposition until Darwin, in 1859, explained 
it in his theory of Natural Selection. Formerly, one school of 
investigators referred it to an originally created specific 
peculiarity; while another declared it to be due to the direct 
action of climate, food or soil. Hyen at this date there are 
those who still hold one or the other of these views. Both 
arguments are untenable, the former because it raises a bar 
to reasonable and intelligent inquiry, and the latter because it 
fails to satisfactorily explain all the varied phases and 
phenomena, and is, moreover, contraverted by well-known 
facts. The gradually increasing change of disguised species 
from a general harmony with surroundings to precise imitation 
of particular objects, is rather to be accounted for by the laws 
of a struggle for existence, and the consequent survival of the 
fittest. Protective colouration cannot be fully understood by 
persons who have given no study or consideration to the 
varying tints of nature. ‘lo see a brilliant specimen in a 
cabinet is one thing, but to note it in the bush, amid its 
natural surroundings, is altogether another. Indeed, the vivid 
colour that makes an animal conspicuous in a collection, is often 
