Attempts at flight and liberation from unwonted compulsory positions or narrow confinement, also deserve special attention. Many a person who has put a star-fish into a cage and fancied that he was assured of its possession, has been disappointed on finding that the animal had effected its escape through the meshes. But star-fishes have, in consequence of their abhorrence of the air, been made to creep into the narrow necks of bottles filled with water. Professor Preyer, for example, thrust two of the arms of a common star-fish species (_Asterias glacialis_) into a tube filled with salt water leaving the three other arms exposed to the atmosphere outside; and although it would have been impossible to force the animal into the tube without crushing it, the three arms exposed to the air were also pulled in within the space of three minutes. If the tube was placed perpendicularly in water the animal quickly crept out again. The performance seemed utterly impossible, for each single arm of the star-fish was almost as thick at its base as the greatest width of the tube, and yet three of these arms had to pass in side by side. This was made possible by the animal emptying during the passage all the numerous water-vesicles in the interior of the arms which serve to fill and to empty the distensible pedicels therein; the star-fish, after the expulsion of the water, becomes very soft in all its parts and does not harden again until it has forced itself completely through and refilled itself with water. In order to accomplish these emptyings, bendings, turnings, and rollings, thousands of muscular fibres must work in harmony within the body of the animal. This experiment was also successfully carried out with other star-fishes, but I cannot agree with the observer when he says that in so doing he brought the animals into a completely new and hitherto unexperienced position. In their haunts on rocky coasts they must assuredly often have to force their way through narrow fissures and holes; and they must find occasion to make use of the advantages of being able to evacuate water in the case also of single arms, as when they search with them in narrow apertures and snail-houses.