Poisoning of Cattle. 141 



Further experiments were carried out to determine whether allied 

 species of fungi (mucor) grown under identical conditions woidd 

 produce similar symptoms and whether Diplorlia zca grown on a cellu- 

 lose medium would give rise to tlie condition when the medium was 

 fed. 



All these experiments gave negative results. 



General Conclusions. 



(1) That a disease in cattle characterized by inco-ordination of 

 movement and paralysis is set up by feeding on mealie cobs which 

 are infected with Diplodia zea. 



(2) The cultures of DipJodia zea grown on sterile maize when i 

 fed produce clinical symptoms- indistinguishable from those set up 

 b}^ feeding on infected cobs. 



(3) That the intensity of the symptoms and the mortality depend 

 upon the quantity fed and on the percentage of infection present in 

 the grains. 



(4) That cultures of allied species of fungi grown on maize are 

 incapable of setting up similar clinical symptoms. 



(5) That the causal factor is not the fungus itself, but must be 

 looked for in the material which is formed as a result of the inter- 

 action of DipJodia zca during its development in the starchy content 

 of the maize giains. 



General DESfRiPTiON. 



The following is a brief description of the disease as it occurs 

 under veld conditions: — 



Geographical Distrihuiion. — In Natal the reports of the presence 

 of the disease would appear to be limited to the high veld parts of 

 the country, and in these areas the occurrence of a disease in cattle 

 resembling this condition has been very common during the last two 

 seasons. In most cases it has been impossible to entirely eliminate 

 all other factors, such as poisoning by poisonous plants, etc., owing 

 to lack of opportunity to investigate each outbreak reported, but it 

 may be taken that cases of the disease have occurred in most of the 

 high veld mealie-producing centres of Natal. The losses were most 

 severe during the season preceding these experiments in the Estcourt 

 Division, and it was from this district solely that the material was 

 obtained for experimental purposes. Reports of a few outbreaks 

 have also come to hand from the Ixopo Division, but material obtained 

 from this district failed -to reproduce the disease in animals at the 

 Research Laboratory, Onderstepoort. 



Seasonal Occurrence. — The disease is limited to the late winter 

 months, July to September. This is the period when veld grazing 

 is very scanty, and it is the custom for farmers to turn their cattle 

 at this time into the mealie lands for better food. 



Animals Affected. — The disease is limited to cattle, animals of 

 all ages and sexes being equally susceptible. Some reports have 

 mentioned the fact that sheep were also susceptible, but up to the 

 present it has not been possible to confirm this. Horses, mules, and 



