The reason given is that the ancient wool is so desiccated as to be no longer nutritious.
"The Tapestry Book"
Helen Churchill Candee
The meals, consisting of tinned meat and biscuits, with eggs and sometimes a small, lean, and desiccated chicken, are very scanty and very monotonous, but the air is so dry and fresh and bracing that one seems to find meat and drink in it.
"Impressions of South Africa"
James Bryce
Then you must increase your fire so that the spirits may pass, over, until the matter in the retort is quite desiccated.
"The Memoires of Casanova, Complete The Rare Unabridged London Edition Of 1894, plus An Unpublished Chapter of History, By Arthur Symons"
Jacques Casanova de Seingalt