The granulogramme of neutrophil cells was studied in three groups of guinea pigs inoculated with an equa] dose of an avian,a bovine and a human standard strains of tuberculosis, respectively. A 4th group was served as non infected controls. Ten animals from each of the infected groups were examined weekly. Result srevealed some characteristic findings which could be taken as criteria for differentiating the three types of TB. bacilli. Such findings were
ngs were observed before the development of tuberculin reaction.