So far as I have been able to find, very little work, if any, has been done to ascertain the resistance of ticks to the gases usually employed in fumigation. This is probably because fumigation for the destruction of ticks is not, under ordinary conditions, a practical method. There recently arose, however, a question at Lourenço Marques (Portuguese East Africa), as to whether ships bringing cattle from Madagascar could be cleaned of the ticks which might have dropped from the cattle and be thus rendered clean for use in the transport of clean cattle for breeding purposes. The port authorities possessed a “Clayton Fumigating Apparatus” for use in disinfecting plague-infected ships and it was suggested that this system be tried for the purpose. Several tests were accordingly carried out with the co-operation of the Chief of the Veterinary Service, the Port Doctor, Municipal Officer of Health, and several local medical men. The “Clayton” being a standard system of fumigation, I will not enter into a discussion of it.