Though no rattle is ordinarily developed until the snakeling is some months old, several cases are on record where young snakes have been born with the ‘button,’ and even with perfectly formed links. Mr. Benjamin Smith Barton, an American who wrote a good deal about the Crotalus, communicated to Prof. Zimmermann in 1800 that he had found in a parent some young ones with three rattles, i.e. ‘links,’ each. Similar and more recent cases are on record.
Transparent rattle
(p. 296), held against
the light.
In colour a rattle is of a dark brown, or dull rusty black, occasionally lighter when fresh and uninjured, and then more plainly displaying its horny texture. In the Mexican rattle (p. 296) the links were semi-transparent; sufficiently so to enable us to trace the form of the interior links if held against the light. This afforded an admirable opportunity to comprehend the structure and the production of the sound, which is simply and truly a rattling of these loosely-fitting links as they are partially embraced, each one by the previous link. That is to say, each new link grows up into its predecessor, pushing it forward towards the tip of the rattle. Through this unusually clear rattle you can trace each link passing up and fitting into the preceding (prior) one, just as so many thimbles or cups would fit into each other. Only, in the case of thimbles or cups, there is nothing to keep them in place, and the slightest shake would detach the whole pile; whereas the lobes or bulging sections of each link prevent any such detachment in a rattle, except by force or accident.
The next is the rattle of a small Oregon snake. This, as is observable, is old and very much worn; so much so, indeed, that one has to handle it with care. It is, however, pulled apart intentionally to show that the links vary in form from those of the tapering specimen. Any rattle can thus be separated without much effort, as, owing to the elasticity of the substance, not much resistance presents itself. The links are just loose enough to produce that sibilant effect, like the rustling of dry leaves, or of ripe beans in a pod; or still more, like the seed vessel of our own native plant the Yellow Rattle, Rhinanthus Crista galli, and the American ‘Rattle-Box,’ Crotalaria sagittalis.
Small divided rattle.
Yet just so securely fitting it is as to permit of the continual vibration without loss of links.
What we see, therefore, is only the base or lower lobe of each joint, the rest running up into the next two or even three bases, as may be traced in the section here given.