A Book of Natural History - Young Folks' Library Volume XIV. by Various
page 62 of 358 (17%)
page 62 of 358 (17%)
![]() | ![]() |
|
or calf at a birth, and seldom produce more than a couple. Moreover,
in all these higher cases alike, the young are fed with milk by the mother, and so spared the trouble of providing for themselves in their early days, like the young codfish or the baby tadpole. Starvation at the outset is reduced to a minimum. It is interesting to note, too, that anticipations of higher types, so to speak, often occur among lower races. An animal here and there among the simpler forms hits upon some device essentially similar to that of some higher group with which it is really quite unrelated. For example, those who have read my account of the common earwig (given in the sixth chapter of "Flashlights on Nature") will recollect how that lowly insect sits on her eggs much as a hen does, and brings up her brood of callow grubs as if they were chickens. In much the same way, anticipations of the mammalian type occur pretty frequently among lower animals. Our commonest English lizard, for example, which frequents moors and sandhills, does not lay or deposit its eggs at all, but hatches them out in its own body, and so apparently brings them forth alive: while among snakes, the same habit occurs in the adder or viper. The very name _viper_, indeed, is a corruption of _vivipara_, the snake which produces living young. Still more closely do some birds resemble mammals in the habit of secreting a sort of milk for the sustenance of their nestlings. Most people think the phrase "pigeon's milk" is much like the phrase "the horse-marines," a burlesque name for an absurd and impossible monstrosity. But it is nothing of the sort: it answers to a real fact in the economy of certain doves, which eat grain or seeds, grind and digest it in their own gizzards into a fine soft pulp or porridge, and then feed their young with it from their crops and beaks. This is thus a sort of bird-like imitation of milk. Only the cow or the goat takes grass or |
|