Philadelphia, and his family life was very happy.
Horner devoted himself closely to his teaching, to the development of the mu- seum of anatomy, started by Wistar, and to scientific study. He also established a medical practice of considerable mag- nitude, and was a successful surgeon. During the cholera invasion of 1S32, Hor- ner was made a member of the Sanitary Board of the city. He made a special study of the lesions produced by cholera in the mucosa of the intestines and show- ed by means of microscopic study of specimens injected with water that especially severe injuries are suffered by the epithelial layer. He published an account of his method of study and the results in 1834 in the "American Journal of the Medical Sciences." He was one of the first medical men in the country to make practical use of the microscope.
Horner's chief attention, however, was given to the study of anatomy rather than pathology. He was untiring in the preparation of specimens and at his death his collection is said to have rivalled those of some of the better museums in Europe. He bequeathed all his specimens, together with his instruments and apparatus con- nected with the dissections to the medical department of the university, a donation valued at some eight or ten thousand dollars. It formed the larger part of the collection known as the Wistar and Hor- ner Museum, subsequently housed in the Wistar Institute of Anatomy at Philadelphia.
His chief claim as an original investi- gator rests upon the discovery of the muscle which he called the " tensor tarsi " and which is frequently called the muscle of Horner. He was led to this discovery because the common account of the appa- ratus for lachrymation did not seem to him to explain fully the phenomena of that function. He accordingly sought for and found a special muscle situated on the posterior surface of the lachrymal ducts and sacs. His discovery was ac- cepted as such by a number of European
anatomists, but others pointed out that the muscular apparatus described by Horner had previously been described by others, though not exactly as Horner described it; several indeed have denied the existence of the muscle as an inde- pendent structure. He is, in any case, justly entitled to credit for calling atten- tion to the structure and pointing out its physiological bearings. Horner's orig- inal articles on the subject appear in the ■'London Medical Repository" for 1S22 and in the " American Journal of the Med- ical Sciences" for 1S24.
Horner also investigated tlie anatom- ical basis of the peculiarly intense odor of the negro and found that the glands of the axilla in the black race exist in much larger numbers and are much more greatly developed than the white. ("American Journal of the Medical Sciences," vol. xxi p. 13).
Horner in addition made contributions on the musculature of the rectum, and on a fibro-elastic membrane of the larynx which he called the " Vocal or Phonetic Membrane."
As a teacher," Dr. Horner was not fluent, copious in language, nor had he any pre- tentions to elocution, but he was a very excellent teacher of anatomy. His plan was, to a certain extent, novel. He com- posed a text-book, which was a most com- plete but concise treatise on "Anatomy."
"It was written in strict reference to the course of study pursued in the Univer- sity of Pennsylvania, and was kept in as compendious a state as possible, so that there should be no unnecessary loss of time in reading it."
Horner was throughout life deeply religious. In 1S39 he united with the Roman Catholic Church, and in 1841 was active in the establishment of St. Joseph's Hospital. He labored against considerable physical disabilities, as he suffered from an affection of the heart. In 1840 he visited Europe in company with Joseph Leidy, and returned much benefited in health. He soon, however, began to suffer again. Finally, in January, 1853, he had to abandon his lectures.