The Mongolia was due at Bombay on the 22nd; she arrived on the 20th. This was a gain to Phileas Fogg of two days since his departure from London, and he calmly entered the fact in the itinerary, in the column of gains.
If, on the other hand, it profited the young of an animal to follow habits of life slightly different from those of the parent-form, and consequently to be constructed on a slightly different plan, or if it profited a larva already different from its parent to change still further, then, on the principle of inheritance at corresponding ages, the young or the larvae might be rendered by natural selection more and more different from their parents to any conceivable extent.
Differences in the larva might, also, become correlated with successive stages of its development; so that the larva, in the first stage, might come to differ greatly from the larva in the second stage, as is the case with many animals.
The adult might also become fitted for sites or habits, in which organs of locomotion or of the senses, etc., would be useless; and in this case the metamorphosis would be retrograde.