The most interesting feature perhaps of this classification is the post-traumatic constitution. Meyer[153] quotes Köppen's excellent description of this condition as follows:—"Men who have suffered from a cranial lesion in which there has been a severe damage of the brain, with or without an injury to the cranial bones, on their recovery from the immediate results complain especially of all kinds of sensations in the head, which they describe either as pain or as pressure with feeling of crawling or dullness of the head, more or less definitely located at the point where they were hit. They frequently become dizzy, and at times even faint for a short time without any epileptic attack. Although slight attacks of dizziness may recur frequently, epilepsy with typical attacks need not develop. There is further in our patients a great irritability and nervosity. The formerly good-natured or even-tempered persons become irascible, hard to get along with; formerly conscientious fathers cease to care for their family. The irritability at times increases to excessive violence in which actions occur of which they have no remembrance; the nervous system is not only under the influence of psychic irritation but especially susceptible to the influence of alcohol or tobacco, in even small quantities. The working capacity of our patients is very poor. It suffers variously, although such individuals often give an impression of perfect capacity; and since the morbid symptoms are essentially subjective, they always arouse doubts whether they could not do something at least, even if they are unable to work in a noisy shop or on a high scaffolding. It is, however, certain that the patients are very forgetful; in giving orders or doing errands they make the most incredible blunders; frequently everything must be written down. Their capacity for thought has suffered, as is sometimes shown, especially in the great slowness of thought. These patients are unable to concentrate their attention, not even in occupations which serve for mere entertainment, such as reading or playing cards. They like best to brood unoccupied; even conversation is rather obnoxious. This point is so characteristic that it gives a certain means of distinction from simulation, which as a rule does not interfere with taking part in the conversations and pleasures of the ward and playing at cards, which means as a rule too much of an effort for the brain of actual sufferers. The patients are usually advised to take light physical work, but even there they are perfectly useless. Excessive sensitiveness of their head obliges them to avoid all work which is connected with sudden jerks, bending over is especially troublesome; and there is hardly any physical work in which this can be avoided; the blood rushes to the head, headache increases, dizziness sets in and the work stops. Patients feel best when in the open air, inactive and undisturbed. There are but few objective signs,