Carl Linnaeus, The Lapland Journey, translated by Peter Graves (Edinburgh: Lockharton Press, 1995), p. 118.
The Mountains [1], 09/07/1732, ¶615:
When a reindeer walks, a clicking noise comes from its foot. I wondered about this and tried to find the reason but, when I asked, they all answered that it was because Our Lord has created him like that. I asked in what way Our Lord has created him so as to produce a click, but Forbes had no answer to this.1 I took hold of the ankle-joint, pulled it, bent it, stretched it out and pushed it together, but still no click could be heard. By and by I discovered that it is caused by the fact that the hooves themselves are hollowed out on the inner sides. When the reindeer is standing on its feet, the hoof is splayed apart but, as soon as the foot is moved backwards, the points of the hoof strike together and thus make a clicking sound – a fact that I was fortunate enough to establish with my own hand on the animal’s foot.