In what this predisposition consists is not always easy to say. As the tubercle bacillus grows in the tissues, it is by preference an anaërobe, and it seems to be lowered in activity or banished by access of oxygen. It has been shown that in those individuals in whose pallid skin, long bones, flabby muscles, and pale conjunctivæ we recognize a predisposition to this disease, the heart is disproportionately small as compared with the weight and size of the lungs. This means a relatively feeble pumping power, and is perhaps the best explanation for what is accepted as a fact. The _mucous membranes of the nose_ and _throat_ are usually the first lodging places for germs carried by the air, they finding here the warmth and moisture necessary for their detention, development, and growth. As long as these membranes are unbroken and healthy, infection is rarely possible; but let tubercle bacilli become caught in the crypts of the tonsils or in adenoid tissue in the nasopharynx, and the other disturbance, set up by irritant organisms of various species, will usually bring about conditions favoring their growth and incorporation into the living tissues. This lymphadenoid tissue is often the port of entry for these organisms. The explanation for local and surgical tuberculosis in bones and other accessible tissues probably is connected with causes determining at these points an area of least resistance, in which the germs find tissues more susceptible than elsewhere, and in which they may live and thrive. Not the least interesting and important of the considerations regarding tuberculous disease is the possibility of an _acute outbreak of tuberculosis after long latent or chronic manifestations of the disease_. This means, in effect, the onset of _general miliary tuberculosis_ which soon terminates fatally, and death is not the infrequent result of such extremely rapid outbreaks from tuberculous disease of joints, bones, ovaries, etc. For the disease when it has assumed this extremely rapid type there is, so far as known, no relief.