8 BULLETIN 65, U. S. DEPARTMENT OF AGRICULTURE. 



On account of this very old and very plausible theory so often 

 advanced, that the disease is due to toxic substances existing in 

 damaged grain and fodder, a number of species of fungi were isolated 

 during the past year from damaged corn and forage and grown on a 

 sterilized corn medium or alfalfa infusion in an effort to produce some 

 toxic substance that would create disease when fed to horses. The 

 pure cultures were allowed to grow for periods of one month's dura- 

 tion, in flasks containing 250 cubic centimeters of the nutrient 

 medium, and the contents of one flask were fed each day for periods 

 of 30 days, along with a sufficient quantity of sound corn and hay to 

 make a normal ration; but no symptoms have thus far developed 

 in the experiment animals, although only about oue-h^lf of the number 

 of pure cultures isolated have thus far been used in this experiment. 



It is possible that laboratory conditions alone can not be made to 

 parallel sufficiently close those which exist naturally in the growiag 

 plants, and that toxic substances which might be produced ia a 

 natural state would not be generated in a corn-meal medium in the 

 laboratory. The by-products of the growth of both fungi and bacteria 

 on corn and forage should certainly receive more consideration ia 

 future work. In view of the above information it must appear to 

 the unbiased mind that the cause of forage poisoning remains an 

 obscure and puzzling problem. 



OCCURRENCE. 



Like cerebrospinal meningitis of man, forage poisoning occurs in 

 sporadic as well as enzootic and epizootic forms. The sporadic 

 cases occur either in different locahties from the epizootic out- 

 breaks or in such sparse numbers as not to amount to an enzootic. 

 Thus the outbreaks are quite variable in extent and severity. Some- 

 times they become very widespread, causing heavy losses, as in the 

 recent outbreak in Kansas and Nebraska, while at other times there 

 are only sporadic cases. Liebener beheves that the development of 

 the cause of the disease in Germany is favored by the rainfalls and 

 warmth of the earth during summer and autumn. No conclusive 

 evidence has ever been presented to indicate that the disease is ever 

 transmitted directly from one horse to another. Sick animals have 

 been placed alongside of susceptible horses in the same stable without 

 conveying the disease to the latter, and healthy horses have been 

 placed in stalls previously occupied by animals which died of the 

 disease, and have eaten from the same mangers without previous 

 disinfection, but in no case has the disease been transmitted in this 

 manner. In the recent outbreak in Kansas it was quite noticeable 

 that livery and other work horses were not affected so long as they 

 were fed on clean, dry forage, although they were constantly exposed 



