Until the last only the voluntary muscles are involved. Finally, however, there are spasms of the accessory respiratory muscles and of the diaphragm. Death is usually produced by involvement of these muscles analogous to those of the others, and results usually from _apnea_ or _suffocation_. During the last hour or two perspiration may be copious and the temperature may rise. _Chronic tetanus_ is characterized throughout by a milder and much more prolonged series of symptoms. The period of incubation is much longer, and, while the general program of the acute form is adhered to, it is of less severe degree and is spread over a longer time; in fact, cases covering two months or more are reported. In chronic tetanus the prognosis is much more hopeful than in the acute form. The wound is but slightly, if at all, affected. In some cases it will be found to have healed before the onset of the disease. If suppurating or open, its evidences of repair will be found unsatisfactory and some indications of septic infection may be noted. Pricking or needle sensations may be subjective phenomena. =Prognosis.=--Prognosis is almost invariably bad; if patients live more than five or six days it is thereby improved. =Postmortem Appearances.=--These are rarely distinctive. In most instances there are evidences at least of hyperemia, if not of more active changes, in the upper portions of the cord. Less often slight changes have been noted in the brain, consisting, in some measure, of disintegration and softening. Evidences of ascending neuritis in the nerve trunks leading to the injured area have been claimed in some instances. Few if any distinctive postmortem changes can be described as due to this disease. =Diagnosis.=--The diagnosis should be made as between _strychnine poisoning_, _hysteria_, _hydrophobia_, _tetany_, and, in the beginning, from pharyngitis, tonsillitis, etc. When the disease is fully developed it is not likely to be mistaken for anything else. Tetanus may be simulated by _hysteria_, but in this event the phenomena will be so uncertain, and the evidences of organic disease so essentially lacking, that it is not likely that mistake can occur.