Throughout the world, several hepatogenous photosensitisation diseases of ruminants are characterised by the presence of birefringent crystals in and about the bile ducts. These include photosensitisations caused byTribulus terrestris(1) (geeldikkop of sheep in South Africa),Nurthecium ossifrugum(2).(alveld of lambs in Norway),Agave lecheguilla(3)(4),Brachiaria decumbens(5) and severalPanicumspecies such asP miliaceum(6),P. coloratum(7),P. schinzii(8)(9), andP. dichotomiflorum(10).