Tegetmeier writes concerning mule mares. He also reports some 'gossip' about Dr Butler of the British Museum and his assertion in The Feathered World that he had seen two mules in foal in a drove of 50 in Spain, and the driver had told him mule mares were often infertile. Tegetmeier remarks 'That a man in his position should publish such nonsense is very unsatisfactory'.