| In vertebrates finally, the organization of muscles into myotomes for swimming has long been considered of crucial adaptative importance. |
|
| These adaptative responses are known to be governed by reactions in which the light-sensitive pigment phytochrome plays a part. |
|
| The shortage of oxygen at high altitude, especially above 12,000 feet, is so physiologically demanding that it imposes deep adaptative changes even within the cells of the body. |
|
