Vietnam or Thailand ? Vote for the TOP Country of the Week !
Updated: May 29, 2025
These foetal structures are minute in size, and never cut the gum, but are reabsorbed without ever coming into use, while no other teeth succeed them or represent them in the adult condition of those animals. Yet this rudimentary wing contains bones which are miniature representatives of the ordinary wing-bones of birds of flight.
Nay, we may even have to admit that, in two points out of four, the inherited effect of use and disuse on successive generations is exactly opposite to the immediate effect on the individual. Among fowls the wing-bones have lost much in weight but little or nothing in length which is the reverse of what has occurred in ducks, although disuse is alleged to be the common cause in both cases.
The thickening of the wing-bones has actually more than kept pace with any increase of weight in the skeleton, in spite of the effect of individual disuse and of the alleged cumulative effect of ancestral disuse for hundreds of generations.
If the relative shortening is attributed to a heavier skeleton, then the apparently reduced weight of the wing-bones is fully accounted for by the same circumstance, and disuse has had no inherited effect. Another strange circumstance is that the wing-bones have diminished in length only.
Word Of The Day
Others Looking