Anat'omy, the science which treats of the structure of animals and plants, is divided into numerous branches. Animal anatomy treats of the structure of animals; vegetable or plant anatomy, of the structure of plants; while human anatomy pertains to the structure of the human system. Comparative anatomy relates to the study of animals with a view to comparing their structure with that of the human body or with that of animals of different orders. Previous to the Christian era, little was known of the structure of the human system. Most peoples held the body sacred after death and dissection was not allowed. The earliest dissection was among the Greeks, about 450 B. C. At this time Hippocrates and his school obtained some knowledge of the skeleton and the larger internal organs. Dissection was first practiced in public at the Alexandrian School, where considerable advance was made in the knowledge of human anatomy, but prejudice against the practice was so strong that it was given up and nothing further was achieved for several hundred years. In the thirteenth and fourteenth centuries the value of dissection for those studying medicine became evident, and the rulers of leading European nations ordered a certain number of dissections in the medical schools each year. From this the practice became general in all universities having medical schools attached to them. At the present time the science of anatomy has reached a high degree of perfection in all the medical colleges of America and Europe, and each of the branches of human anatomy has been itself divided into numerous subdivisions; so that physicians who wish to become specialists, after obtaining a general knowledge of the human system, confine their investigations to one branch, such as histology, or to the eye or the brain and nerves. Anatomy is closely related to surgery, since the successful surgeon must be acquainted with the position and structure of every organ in the body. See ABDOMEN; BRAIN; MUSCLES; NERVES; SKELETON and many kindred topics.