YEASTS AND MOLDS 



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dried excreta containing the spores about, and those which lodge upon the 

 barley straw and barley grains (and no doubt also upon other cereals and 

 other forage plants) on entering the intestinal tract of susceptible animals 

 which may happen to feed upon such contaminated material, will multiply 

 in the manner already stated. The probabilities are that wild rabbits, 

 rats and mice, as well as sheep, cattle, domestic rabbits and guinea pigs, 

 are the carriers and disseminators of the infection. 



It is evident that not all animals, even of the same kind, are equally 

 susceptible to the infection and the poison formed, as not all animals died 

 which were fed approximately equal amounts of the spore contaminated 



Pig. 80. — A toxigenic saccharomyoete responsible for the fatal poisoning of sheep. 

 It is an obligative parasite and will not develop outside of the intestinal tract of sus- 

 ceptible animals (sheep, goats, rabbits, guinea pigs and probably other herbivora) . a, 

 the vegetative cells which occur in the stomach, where they grow and multiply by 

 budding, b, the spore bearing cells, showing numerous transverse markings, some 

 heavy and the'rest light. The sporangium breaks across along the heavier lines and 

 the spores are thus allowed to escape as shown at c. d, a group of the small spores, 

 measuring about four microns in length. 



material. It is also evident that a definite number of the spores must be 

 taken in with the food in order to produce fatal intoxication. It is further 

 evident that theorgam'sm in question does not grow and multiply outside of 

 the stomachs of living susceptible animals. As soon as the animal dies the 

 vegetative cells also die, only the matured spores surviving, as already 

 explained. The barley and barley screenings themselves contain no toxin 

 as was proven experimentally. 



A careful microscopical examination of the ground alfalfa, barley, bar- 

 ley screenings and "black strap "molasses samples submitted to me proved 

 the absence of poisonous weeds. The barley, and especially the barley 

 screenings contained a considerable amount of barley smut (a fungus 

 belonging to the Ustilago genus) but not enough to produce fatal poisoning 

 or even toxic symptoms, and none of the symptoms of the experimental 



