Unfortunately, a dozen book-makers and a thousand journalists seek no farther than encyclopedias when they are ‘reading up’ a subject; and not until too late, if at all, or after long searchings and a realization of the importance of dates, do these wide spreaders of information discover the error. Compilers of articles for encyclopedias are always limited as to space, and often as to time; and life would not be long enough to wade through Zoological Records covering fifty years, or Annales des sciences naturelles which date from 1824 to the present time. Only, the compilers of articles on the Reptilia should surely have known of Mr. Bell’s Coluber natrix, and of the Paris python, and of the Amphisbæna of the Zoological Gardens, all ophidian celebrities in their day.
The mention of the Zoological Gardens reminds me of my promise to conduct my readers thither as an agreeable change from the book-shelves. Therefore, without further wearying them with the conflicting statements of fifty writers, let us repair thither, and see what Holland, the keeper, tells us about his thirsty snakes.
First, we observe that most of the cages are furnished with a tank or a pan of water, and this not for the watersnakes only. Many of the others, also, are lying in their bath, coiled up in apparent enjoyment. Questioning the intelligent keeper, he tells us that when fresh ophidian inmates arrive, they almost invariably go to the water, and though for a time they refuse food, they always drink. On several occasions some have drunk so eagerly that the water has visibly sunk in the tank. These were the larger snakes, of course. He does ‘not believe they would live without water.’ He then tells us the story of the Amphisbæna over again, the snake that lived for six months on milk only, and which was chronicled in the zoological magazines of the day, and has figured in books ever since.
Mr. Mann confirmed all these facts in his own ophidian pets, and going to see these interesting individuals, we felt no doubt about it when a saucer of water was in the way.
But I do feel inclined to doubt whether the use of the tongue in ‘lapping,’ as it has been called, is not rather to moisten that organ than to quench the thirst. We shall see in the following chapter what it does for its owner, and we shall see the necessity for this delicate organ to be well lubricated. Both it and its sheath require to be constantly moistened; how else could it glide in and out with that wonderful activity? how in a dry and parched condition could it retain its exceeding flexibility and delicacy of perception?
Unfortunately, the position of the tanks in the cages at the London Zoological Gardens, and the stone ledge in front of them, prevent the visitors from watching the actions of the snakes in the water, either when swimming or drinking. Occasionally one of the inmates of the larger cages may be seen in a pan of water, though their motions are necessarily restricted there. One day, however, the yellow Jamaica boa, when drinking from the pan, afforded an excellent opportunity for observation. And he was a long time imbibing. There was no perceptible action of the lips, which were barely parted. The snake kept its mouth just below the level of the water, and the only action or movement seen was at the back of the head, or on each side of the neck, like a pulsation, as the water passed down in short gulps. This is the ‘suction’ which writers describe, a drawing in of the liquid; but the lips do not take part in the act. When, therefore, we read that snakes drink both by lapping and also by suction, we may surmise that the former is for the benefit of the tongue, the latter of the body; and a large quantity of liquid is often drawn in by this sort of suction, very distinct from ‘sucking,’ the reputed way of enjoying milk from the living fountain, and a process impossible to creatures that have not soft lips and a broad tongue. The Jamaica boa drew in those perceptible gulps for a long time, then raised his head, and rested awhile, and presently drank again, and this several times while we were watching. It was what Dumeril described à la régalade.
Mr. Sam Lockwood of New Jersey, writing in the American Naturalist, vol. ix. 1875, describes the pine snake drinking. ‘It lays its head flat upon the water, letting the lower jaw just sink a little below the surface, when with a very uniform movement the water is drawn up into the mouth and passed into the throat. It is true drinking, like that of a horse.’ One that he watched drank five minutes by the clock without taking breath. Then it paused, looked about for three minutes, and then drank again for five minutes more. ‘In all, it drank a little over a gill. Previously it has been without water for four weeks.’
In size this pine snake differs not much from the Jamaica boa (Chilobothrus inornatus), that we watched at the Gardens, and the manner and time were very similar. True, we did not time him by a watch, nor could we tell exactly how much he drank, nor how long previously he had been without drinking; but, at a guess, he could not have been much less than five minutes without taking breath. Anguis fragilis, that lapped seventy times, and stopped, and lapped again, must also have been some minutes without breathing, because hers was the most leisurely lapping I ever saw.