Charles Darwin Quote
These [calciferous] glands (see Fig. 1), judging from their size and from their rich supply of blood-vessels, must be of much importance to the animal. But almost as many theories have been advanced on their use as there have been observers.
Chapter 1: Habits of Worms, (p. 43) - The Formation of Vegetable Mould through the Action of Worms (1881)