Tuberculosis used to be considered the hereditary disease _par excellence_. Entire families were carried off by it, and, seeing a tuberculous father or mother and then tuberculous children, it was assumed that the infection had been transmitted to the children by heredity. As a matter of fact, the disease was spread by infection. In former years, little care was exercised about destroying the sputum; the patients would spit indiscriminately on the floor, and the sputum, drying up, would be mixed with the dust and inhaled. Often the children crawling on the floor would introduce the infective material directly, by putting their little fingers in their mouths. It is now known that tuberculosis is not a hereditary disease, that is, that the germs are not transmitted by heredity. _The weak constitution_, however, which favors the development of tuberculosis, is inherited. And children of tuberculous parents, therefore, must not only be guarded against infection, but must be brought up with special care, so as to strengthen their resistance and overcome the weakened constitution which they inherited. That a person with an active tuberculous lesion should not get married goes without saying. But, it is a good rule to follow for a tuberculous person not to marry for two or three years, until all tuberculous lesions have been declared healed by a competent physician. As a rule, a tuberculous patient is a poor provider, and that also counts in the advice against marriage. Then sexual intercourse has, as a rule, a strong influence on the development of the disease. Unfortunately the sexual appetite of tuberculous patients is not diminished, but, rather, very frequently heightened; and frequent sexual relations weaken them and hasten the progress of the disease. As to pregnancy, that has an extremely pernicious effect on the course of tuberculosis, and no tuberculous woman should ever marry. If such a one does marry or if the disease develops after her getting married, means should be given her to prevent her from having children. During the pregnancy, the disease may not seem to be making any progress--occasionally the patient may even seem to improve--but after childbirth the disease makes very rapid strides and the patient may quickly succumb. In the early days of my practice I saw a number of such cases. If precautions are taken against pregnancy, then permission to indulge in sexual relations may be given, provided it is done rarely and moderately. If a patient who has tuberculosis conceals the fact from the future partner, a fraud is committed, and the marriage is morally annullable. It has been declared legally annullable by a recent decision of a New York judge. =Heart Disease=