This photograph depicts the colonial morphology displayed by Gram-negative Yersinia pestis bacteria, which was grown on a medium of chocolate agar, for a 72 hour time period, at a temperature of 25°C. Note that PHIL 12470 displays a closer view of these Y. pestis bacterial colonies. See also PHIL 12468 for the appearance of Y. pestis colonies grown on the same medium, and at the same time temperature, but for a lesser time period (48hr); PHIL 12471 displaying growth on the same medium, but for a lesser time period (48hr), and at a greater temperature (37°C); PHIL 12472 displaying growth on the same medium, for the same amount of time, but at a greater temperature (37°C); PHIL 12473 displaying Y. pestis colonies grown on the same medium and temperature, but at one-third the time (24hr).