The differences found between the eggwhite hypersensitiveness of tuberculous guinea pigs and the tuberculin hypersensitiveness induced us to continue our former work1 on the protein antigens of the tubercle bacillus. We publish this preliminary report because the detailed examination of the observations made requires considerable time. The following extracts of a virulent freshly cultivated strain of tubercle bacilli were examined in their relation to the antigen antibody reactions and the tuberculin reaction: Direct extract was obtained with distilled water. The growth on glycerin bouillon was washed without being broken up with distilled water, and filtered quickly, then suspended and slowly ground for two days in distilled water with the addition of some chloroform. If the culture is washed longer with distilled water and filtered slowly one obtains an extract of very slight efficiency and very little protein content. This was the reason that in our first publication, we overlooked the interesting properties of this extract. After being filtered and washed again with distilled water the bacillary mass was dried and extracted with ether (2 days) and alcohol (twice during 3 hours), then extracted twice with distilled water, being thoroughly ground (5 days) (extract after defating), and six hours (including filtration) with 0.2 per cent NaOH (NaOH extract). With every extract several sera were obtained from tuberculous guinea pigs in the first weeks after the infection. The complement fixation, precipitation, and tuberculin effect of the extracts and different precipitates of them with HCl, alcohol, NaOH. etc., were examined. None of the sera has given complement fixation with the alcohol extract of the tubercle bacillus, or precipitation with the purified carbohydrate precipitable substance, but they gave strong precipitation with the HCl precipitates of the extracts.