288 THE WORLD OF THE SEA. 
in the economy of Nature, no useless organ can be kept in repair ; 
hence the eye closes, and the creature is condemned to a life of 
blindness. This is not the only instance of this peculiarity: it is 
often the case with the young of the infusores. Ehrenberg par- 
ticularly instances the young Eudorina, which is furnished with 
a large red eye—a distinction not enjoyed by its parent. 
Many clever naturalists have entertained the idea that man 
represents the perfect organism of Nature, and that the lower 
animals are, as it were, embryos of this perfect idea, arrested at 
different stages of its development. A beautiful theory, but not 
true; for here we have young animals better developed than their 
parents. This is not an advancement, but a retrogression. And 
besides this objection, the different parts of an animal seldom 
or never exhibit the same phases of advancement: one organ is 
in a more complete state, and constructed upon a higher model 
than another. Some creatures are superior to others in the 
development of their respiratory apparatus, when probably the 
animal which is inferior in this sense is superior as to the arrange- 
ment of its nervous system. The laws which regulate the general 
harmony of the animal economy are far too complicated to admit 
of being enunciated in a single sentence. In fact, the organisation 
of each species seems to have a law peculiarly provided for it. 
But to return to our subject. The cyclops larve are almost 
triangular, and are covered with a large shield. In front they 
put out two little divergent horns, and behind ‘them they drag a 
double tail. Their sides are furnished with six pairs of oars, the 
last two pairs being much larger than the others. The larva 
does not grow very rapidly; but when it reaches its change of 
life, the eye closes, the oars, the antenne, the tail, disappear, its 
vagabond life comes to an end, and, like its forefathers, it finds 
itself fixed to some solid hold, where it assumes the ringed pedicle 
and the mitred head-piece of its race. 
The class cirrhopoda contains other specimens of animal life 
than the anatifera we have described; and, as in every other 
family, the features are altered in almost every conceivable manner. 
Some have no stalk, but the shelled body adheres directly to the 
rock. The shell is not always composed of five pieces, but some- 
