Abstract
During experiments upon the intestinal absorption of B. prodigiosus and various types of yeasts in rats, it was found that many of the plate cultures of the contents of different levels of the gastrointestinal tract were sterile. To determine whether these plates were actually sterile or whether forms of microbes were present in a phase which-did not grow appreciably, we subjected such apparently sterile cultures to the serial plating technic described by Hauduroy. 1 About 0.5 cc. of sterile nutrient broth is taken up in a capillary pipette, the slender part of which is about 3 inches long. After discharging all the broth onto the surface of the plate from which transfer is to be made, the pipette is held so that the side of the Bunsen flame just touches it about 2 inches from the tip. Softening of the glass and the weight of the tip operate to bend the pipette into a spreader which is used to scrape the discharged broth back and forth across the surface of the plate, thereby washing off whatever microbic elements may be present. The same pipette is used to draw up the washings, to discharge them upon the fresh plate, and to spread them over its surface. We have found this technic superior to that of using 2 pipettes and 2 spreaders for this simple operation. Practically all of the apparently sterile plates selected for this study were derived from the stomach or duodenum of the animal; an occasional plate made from the first part of the jejunum was also sterile. These plates were all observed for at least 48 hours (many of them for 60-72 hours) and did not show detectable growth under a hand lens or low power of the microscope.
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