After a review of the main theories by various authors on the aetiology and transmission modes of tubercular infection, the paper deals with the discovery of the tubercular bacillus made by Koch and the experiments conducted by his co-worker, Cornet, who concluded that the tubercular bacillus was more concentrated around the subject suffering from open pulmonary TBC. However, it was Flugge who eventually clarified beyond any doubt, after many experiments, the real, direct transmission mode of tuberculosis through droplets of saliva emitted by the sick and which are still known today as Flugge's droplets.