Ordinary microscopic slides of the diseased bread were made with sterile water, and these examined by microscope. This revealed the presence of moulds and mucor spores, yeasts—both the ordinary cultivated and wild—and numerous bacteria. On further examination after incubation at suitable temperatures, most of the above-mentioned proved to be just the common micro-organisms existing in flours and bread. Some of the bread was then incubated at 80 degrees Fahrenheit for four days. The piece of bread was then found to be covered with a whitish-colored growth, which later developed into a dark yeasty color and possessed a very peculiar and strong odor. Samples of the flour and yeast used in the manufacture of the bread were treated in a similar manner. In four days the flour specimens showed the same peculiar growth which, in two days, changed to the dark fawn color possessing the same characteristic odor. The yeast, on the other hand, behaved quite normally and developed none of the strange symptoms.
The next step was to try to infect some sterile bread with this peculiar disease, if possible. To this end sterile bread was introduced into Petri dishes, moistened with sterile water, and some of the dish contents sprinkled with flour, and others with crumbs of the diseased bread. The incubation temperatures were 68 and 80 degrees Fahr., respectively. At the lower temperature, as well as at the higher, the cultures were all successful, but it took several days longer in the specimens—at the lower temperature. Various other cultures were now put on, with other media and different apparatus, with a view to isolating the special cause of the disease. All specimens, and also micro-slides from these, had to be examined regularly at fixed periods, entailing, of course, an enormous amount of detail work which cannot here be set forth. Suffice it to say that ultimately by varying the media and mode of cultivation swarms of very minute oval-shaped non-mobile bacteria, and also many rod-shaped mobile organisms, were isolated. By this time all yeasts, moulds, mucors, and other complex growing organisms had been eliminated. To ensure that all the apparatus and media were sterile, blank specimens were put on so as to be parallel with the special culture in each case.