These filterable agents were named bacteriophages (eaters of bacteria) or phage for short. In 1903 he demonstrated that the causative agent of rabies was a filterable virus. It also has a filterable cytotoxic alpha-hemolysin rarely found in other "Proteus" species. In 1906 Arnold Theiler showed that bluetongue was caused by a filterable agent. A method was found to produce a clear, filterable, stable product. A small filterable agent was soon identified as the source of this genetic exchange.