to find that he cannot keep his feet because his concealed syphilis is beginning to affect his nervous system. +Nature of the Tissue Change in Late Syphilis--Gummatous Infiltration.+--The essential happening in late syphilis is that body tissue in which the germs are present is replaced by an abnormal tissue, not unlike a tumor growth. The process is usually painless. This material is shoddy, so to speak, and goes to pieces soon after it grows. The shoddy tissue is called "gummatous infiltration," and the tumor, if one is formed, is called a "gumma." The syphilitic process at the edge of the gumma shuts off the blood supply and the tissue dies, as a finger would if a tight band were wound around it, cutting off the blood supply. Gumma can develop almost anywhere, and where it does, there is a loss of tissue that can be replaced only by a scar. In this way gummas can eat holes in bone, or leave ulcerating sores in the skin where the gumma formed and died, or take the roof out of a mouth, or weaken the wall of a blood-vessel so that it bulges and bursts. The sunken noses and roofless mouths are usually syphilitic--yet if they are recognized in time and put under treatment, all these horrible things yield as by magic. There are few greater satisfactions open to the physician than to see a tertiary sore which has refused to heal for months or years disappear under the influence of mercury and iodids within a few weeks. Still better, if treatment had been begun early in the disease, and efficiently and completely carried out, none of these conditions need ever have been. +Destructive Effects of Late Syphilis.+--Late syphilis is, therefore, destructive, and the harm that it does cannot, except within narrow limits, be repaired. It is responsible for the kind of damaged goods which gives the disease its reality for the every-day person. It is a matter of desperate importance where the damage is done. Late syphilis in the skin and bones, while horrible enough to look at, and disfiguring for life, is not the most serious syphilis, because we can put up with considerable loss of tissue and scarring in these quarters and still keep on living. But when late syphilis gets at the base of the aorta, the great vessel by which the blood leaves the heart, and damages the valves there, the numbering of the syphilitic's days begins. Few can afford to replace much brain substance by tertiary growths and expect to maintain their front against the world. Few are so young that they can meet the handicap that old age and hardening of the arteries, brought on prematurely by late syphilis, put upon them. When late syphilis affects the vital structures and gains headway, the victim goes to the wall. This is the really dangerous syphilis--the kind of syphilis that shortens and cripples life.