vorable to the offspring.

The questions concerning the advisability of marriage which the layman
as well as the physician have most often to deal with are questions
concerning venereal disease. On account of the importance of the
subject, these have been discussed rather in detail under the headings
"Gonorrhea and Marriage" and "Syphilis and Marriage." Other factors
affecting marriage, either in the eugenic or dysgenic sense, will be
discussed more briefly in the present chapter, and more or less in
the order of their importance.

=Tuberculosis=

Tuberculosis, which carries off such a large part of humanity every
year, is caused by the well-known bacillus tuberculosis, discovered by
Koch. The germ is generally inhaled through the respiratory tract, and
most frequently settles in the lungs, giving rise to what is known as
pulmonary consumption. However, many other organs and tissues may be
affected by tuberculosis.

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