The development of the malady is insidious and long continued. As a matter of clinical convenience physicians divide its progress into successive stages although in reality the transitions are frequently variable and ill marked. The symptoms that arise within the first few months or even years are readily controlled by appropriate treatment, but to insure a cure prolonged and most thoroughgoing treatment is imperative. The symptoms disappear so completely after a short period of treatment that it is very difficult to persuade the average patient that he is not yet cured. Two years at least are none too short a period of treatment, yet the majority of patients, fully convinced that they are merely being exploited by the physician as a source of revenue, drift away at the end of a few months. As a matter of fact, however, the germs usually persist long after the obvious symptoms of the disease have disappeared, and in consequence many of the most serious results of syphilis may not manifest themselves for a period of perhaps ten, twenty or thirty years. =Some of the Effects.--=It is now known that _paresis_, also termed general paralysis or softening of the brain, is probably invariably due to syphilis. The work of Flexner and Noguchi on _paresis_ and _tabes dorsalis_ show that always in such afflictions the tissues of the central nervous system have been invaded by the parasite. The original infection, however, may have occurred so long before as to have been almost forgotten by the patient. Thus many an apparently robust man is stricken down in the prime of life. Earlier and prolonged treatment would in all probability have eradicated the germs and thus prevented the mental breakdown, which can not be cured by any known treatment. Postmortem examination always shows that the _Treponema_ has wrought wide-spread damage in the brain. The frequency of paresis may be realized when one learns that in some regions it is responsible for about one-fifth of all cases of insanity sent to hospitals for the insane. It ranks next to the highest as a cause of insanity. Statistics show that in the state of New York more deaths result annually from paresis than from smallpox, tetanus, malaria, dysentery and rabies all combined. In some cases the disease attacks the membranes of the brain and the small blood vessels giving rise to a still different type of mental disorder. Practically all patients with _locomotor ataxia_ owe their condition to an antecedent syphilis. Moreover it is one of the important causes of _arterio-sclerosis_, or hardening of the blood vessels, and is also a prominent factor in certain forms of heart-disease, as well as by no means an unimportant cause of blindness in children.