There is no evidence that any particular occupation acts as a predisposing cause of typhoid fever. Among the 621 patients treated at the Pennsylvania Hospital during the last ten years, were representatives of every branch of industry, and the same fact has been observed at every general hospital, not only in this country, but abroad. There is also no reason to believe that the station in life of itself exerts much influence in predisposing to the disease. The rich suffer equally with the poor. It would appear, indeed, that since the recent general introduction of ill-ventilated water-closets and stationary washstands into the houses of the {245} better classes the liability of the former to suffer from the disease is greater than that of the latter. Persons recovering from an illness or in an infirm condition of health do not appear to be more liable than others to be attacked by typhoid fever. Among the many patients who have fallen under my care only a very few were in ill-health at the time of their seizure. The same fact has been noticed by Murchison and other observers. Indeed, Liebermeister goes so far as to say that typhoid fever attacks by preference strong and healthy persons, while it avoids those suffering with chronic ailments. That this latter class of patients enjoys no immunity from the disease when exposed to its causes is shown by a fact which he himself records. During his service at the hospital at Basle from 1865 to 1871 several of the patients in the medical and surgical wards were attacked by typhoid fever, the cases being especially numerous in two rooms which were situated one directly over the other. Upon investigation it was found that a wooden pipe which extended from the sewer to the roof ran by both of these rooms. The sewer at the point where this pipe ran into it was of faulty construction, and was turned at a right angle, so that the refuse matter collected there. Since this source of infection was made known repeated cleansings, washings, and disinfections have been followed by satisfactory improvement, and Liebermeister believes that if the sewer were entirely altered the infection would disappear.