A naked man with motor neuron disease, walking. Collotype after Eadweard Muybridge, 1887.

"The gait in lateral sclerosis. This gait was studied in Plate 548. The subject was a patient of the University Hospital and was under the care of Dr. William Pepper. His history was as follows :* (* See Philadelphia medical Tmes, October 31, 1885. Clinical Lecture by Professor Pepper.) "H. S., aged twenty-eight years, single, is an engineer by occupation, and had been working on a railroad in Wyoming Territory until three or four months ago, when he came to this city. When a child he had diphtheria, which was followed by dropsy and paralysis. Later he was thrown on a hot stove and severely burned, the scar being visible on the epigastrium. When twenty-two years of age he had typhoid fever. He denies having had gonorrhoea or syphilis, although intercourse with loose women is acknowledged. Careful investigation fails to reveal any trace of specific infection. He has used alcohol in considerable quantities, but has never been intoxicated. He uses tobacco in great excess, smoking as many as fifteen cigars on some days, and chewing a large plug of tobacco every twenty-four hours. His occupation has been an exposing one, subjecting him to extreme alternations of heat and cold. He, however, continued in good health until three years ago. In December, 1882, he first noticed a gradual loss of power in the left ankle. He states that five months prior to this he had injured the left ankle and knee by falling from his locomotive. This kept him in bed for seven days, then apparently he became entirely well. The feeling of weakness on the left side compelled him to throw most of his weight on the right leg. The trouble gradually grew worse, and in November, 1883, he noticed that occasionally the affected leg would suddenly fly backward when he attempted to move it, and that the muscles of the left side would tremble violently in quick clonic spasm. Unless he moved very carefully this occurred at every step. He next observed that he was losing flesh. His height is six feet one and one-half inches, and his best weight has been one hundred and seventy-nine pounds. Three months ago, when this note was made, he weighed one hundred and sixty-five pounds. In July, 1884, the affected ankle was strained, and this was followed by swelling of the foot and leg. About this time, or a little earlier, he noticed that the fingers of the left hand were disposed to contract, so that the hand would remain closed until the fingers were forcibly extended. The contraction was increased by fatigue. This gradually increased until it involved the hand, forearm, arm, and shoulder. At the time at which the photograph was taken, the summer of 1885, the patient presented in addition the following symp toms : He habitually carried the left arm (vide Plate 548) in the semi-flexed position assumed by patients having lateral sclerosis or secondary degeneration of the lateral columns. The left leg was decidedly stiff. When sitting on a chair it was extended. The knee-jerk was markedly exaggerated. The gait was "spastic." The right leg also was somewhat affected. It was somewhat resistant to flexion and tlie knee-jerk was evidently increased. …"—Dercum, loc. cit.