There is considerable mobility of the neck of the porpoise, an animal lacking all outward appearance of a neck. The head can be turned down at an angle of about 45 degrees to the body, and can be turned as far sideways with equal readiness. These motions can be seen at feeding time and when the animals are tossing fishes. There is no evidence that the porpoise can see out of water. In throwing a fish the head is often thrust well above the surface, but the animal seems to be always intent on its plaything, entirely disregarding the visitors leaning over the rail five or six feet away. While a fish thrown into the water is promptly seized, the porpoise pays no attention to a fish suspended by a thread two inches above the surface. If the eyes of porpoises and other whales were fitted for observation above the surface of the water, as are the eyes of seals, they might long ago have learned to use them in the same way.[18] Footnote 18: I do not believe that because the porpoise would not seize a fish suspended above the water, it is evidence that it could not see it. Not being accustomed to take its food out of the water, the animal probably did not know what the fish was. A wounded porpoise which I kept alive for some time on a ship in the Pacific could see my hand if it was brought within a few feet of its eyes. R. C. A. Porpoises instantly recognize any change that may occur in connection with the water level of the pool. The entirely noiseless opening of a distant valve to lower the water is apparent to them and may stop their play temporarily. A pool only thirty-seven feet in diameter does not of course afford space for the high activity of which the porpoise is capable. Nevertheless they often leap three feet or more clear of the surface, sometimes striking the water forcibly enough to throw spray thirty feet into the air. The visitor soon gets the impression that they enjoy life even in captivity and their keepers, while always vigilant as to their needs, have ceased to be concerned about their safety, regarding them as almost domesticated animals. [Illustration: _Photo by E. R. Sanborn._ “The captive porpoises are very lively, and keep swimming day and night, rising to blow usually with each circuit of the pool.” ] The naturally sociable and gregarious habits of porpoises is evidently not lessened by captivity. Sometimes they seize each other by the back just behind the dorsal fin, but there are no tooth marks on any of them and it is probably done in play. The indications are that they are altogether amiable and inoffensive toward each other. The only species of porpoise destructive to its kind is the well-known “Killer” (_Orca gladiator_). Our porpoises were observed mating in January, and again in March and April. It is possible that they will breed in captivity if their lives are not shortened by indoor life.[19]