The etiology of whooping cough has long been an unsolved problem. Many attempts have been made to discover some micro-organism in association with it, but hitherto the results have been very contradictory. In 1906, however, Bordet and Gengou1 described an organism which they obtained in pure culture and offered considerable evidence to show that it was the organism causing the disease. Their results have recently been confirmed by Klimenko.2
The organism they describe is a small, short bacillus, with rounded ends. It stains feebly and shows polar granules with carbol methylene blue. It decolorizes by Gram's method. It is non-motile, aërobic, and grows very slowly and feebly when first isolated, and only on a special medium they devised, composed of glycerin, potato, gelatin and blood. But after several generations it will grow fairly well on other media, and does not require hemoglobin, unlike the influenza bacillus, which it