308 PHARMACEUTICAL BACTERIOLOGY 



spore formations. Since the yeasts are sugar feeders and vegetarian we 

 may expect to find them in plants and in fodder containing more or less 

 sugar, and also for these reasons we may expect to find them parasitically 

 associated with herbivorous animals, less commonly with omnivorous 

 animals and least of all with carnivorous animals. One of the many 

 reasons why our knowledge of food poisoning (in cattle as well as in humans) 

 is so incomplete is because most of the methods of investigation of cases 

 are chemical. Rarely is the microscope brought into play and even when 

 this is done, the work is left to amateurs who usually report negatively, 

 not because there is nothing to report, but rather because they fail to 

 observe or fail to recognize the foreign organisms which may be present. 



The following descriptions of parasitic Saccharomyces will serve to 

 illustrate the points above set forth. In order that the student may 

 realize the remarkable Ufe habits and morphological characteristics of the 

 two parasitic yeasts, he should familiarize himself with yeasts in general. 

 Such information may be gleaned from any of the more complete texts on 

 general botany 'and the special treatises on yeasts and on fermentation. 



The first case pertains to the poisoning of sheep in a San Francisco 

 stock yard. The toxicological examination (chemical) was negative. 

 The following is the report of the microanalyst who was called into the 

 case. 



" I hereby submit a report on the poisoning of sheep which occurred at 

 the San Francisco stockyards, Feb. 12, 1918, and for several days subse- 

 quently. I beg to state that certain phases of the observations made by 

 myself are not finally conclusive. However, the following statements, 

 recommendations and conclusions are warranted, based upon the tests 

 and observations made to date. 



The sheep (some 257 in number) were evidently killed by a toxin 

 (poison) formed in the intestinal tract of the animals, due to the presence 

 of a parasite which belongs to the yeast group (Saccharomycetes). The 

 spores of this organism, which are apparently derived from the barley as 

 well as from the barley screenings, enter the stomachs of the animals, with 

 the food, where they develop into mature vegetable cells, whereupon these 

 multiply quite rapidly (by a process" known as 'budding'). The toxin or 

 poison (evidently an exotoxin) is formed by the growing and budding 

 vegetative cells in the stomach of the animals. The parasite next passes 

 into the small intestine along with the food, where further development is 

 completely checked (due to the alkaline reaction and enzymes present). 

 Spore formation takes place in the large intestine and the spores escape 

 with the excreta. 



The spores are very small, resembling bacteria, and each spore bearing 

 cell forms from fifty to one hundred and more. Air currents spread the 



