In the Veterinary Museum in Skara there is also an Animal Pharmacy. One bottle originating from the 18th century is labelled Tinct. Canthar. and thus contained an extract of Spanish flies. The active substance in such a tincture is cantharidin. The use and effects of this remedy in veterinary as well as human medicine are described. The use of cantharidin in the 18th century was linked to the predominant believe that illness was caused by imbalance of the four humours of the body. Its blistering effect was thought to "draw" superfluous liquid from the body. Its pronounced toxicity made its use to disappear, but it could still be found to be used in veterinary medicine as a blister and by undiscerning people as an aphrodisiac. Recent studies has shown cantharidin to possess antitumour effect--something that Dioscorides noted in his texts from around A.D. 40-80!