EGGS AND EGG-COLLECTING. 131 



colouring of the eggs with their surroundings renders them 

 difficult to find ; and still further, the eggs are laid at a 

 season when they are least likely to be addled by snow- 

 storms. 



On the other hand, we will take the nest of the com- 

 mon Thrush, which, in the first place, is so constructed that 

 the eggs are in no danger of being destroyed by falling- 

 out ; in the second place, they are of such a convenient 

 size and shape, added to the cup-like construction of the 

 nest, that half-a-dozen eggs are hatched by the bird as 

 easily as the normal number four ; in the third place, 

 the depth of the nest and its elevated position generally 

 hide the eggs from observation, so that their blue un- 

 harmonious colour does not really expose them, for it is 

 the close resemblance of the nest to the surrounding objects 

 upon which safety really depends ; lastly, the bird does 

 not breed at a great altitude, and is in consequence enabled 

 to nest much earlier in the spring. 



Pisciculture affords the same inexhaustible evidences of 

 the powers granted to every kind of animal life for the 

 propagation and preservation of its particular kind. Take, 

 for instance, trout : how their colour changes in obedience 

 to that of the bed of the stream or pond in which they are 

 found ; and again, each separate brook produces fish (of the 

 same species) with features of a distinctly different charac- 

 ter, so that they can hardly be mistaken by even the most 

 casual observer. Still further, the trout in a stream of 

 even temperature all the year round, or nearly so, I have 

 noticed spawn much later than the trout of a neighbouring 

 stream liable to be reduced to a very low temperature in 

 winter, and a correspondingly high one in summer ; yet I 

 have discovered no appreciable difference in the size of the 



