The spread of Bact. lepisepticum infection throughout a population of thoroughbred rabbits at a farm in New City, N. Y., was studied over a period of 2 years. The following observations are noteworthy.
1. 50 to 75 per cent of the total mortality was due to Bact. lepisepticum infection.
2. About 50 per cent of the stock was affected locally with Bact. lepisepticum "snuffles."
3. "Snuffles" and mortality rates showed spring and fall rises and low points during the summer.
4. Carrier, morbidity, and mortality rates of various special breeds differed consistently and to a marked degree. All reflected the same seasonal fluctuations as the total population.
5. Individuals within each breed differed in their response to the presence of Bact. lepisepticum; some died of penumonia and septicemia; others developed the local nasal infection, "snuffles"; others became "healthy" carriers; and a few remained uninfected.