His great-grandfather, Carl Ludwig Leidy, was the original American emigrant who settled in Philadelphia County, Pennsylvania, in 1719, and was the founder of Leidytown, still a post office in Montgomery County, formerly Philadelphia County.
At the age of ten years Joseph Leidy was sent to the Classical Academy, a private school conducted by Rev. William Mann, a Methodist clergyman, where he studied English and read Latin and Greek. Joseph even then manifested an unusual interest in minerals and plants and diligently read books on mineralogy and botany. In this pursuit Mr. Mann lent him his support, although he was frequently called upon to admonish Leidy for repeated unexcused absences from school which the boy spent in the hunt for minerals and plants in the rural districts near Philadelphia. It is a noteworthy fact that these excursions into the realm of nature were prompted solely by his eagerness to find the specimens which he had read about. His favorite hunting ground was along the banks of the Schuylkill and Wissahickon. On one of these occasions he strolled into Mr. Henry Pratt's famous grounds at Lemon Hill where he became acquainted with Mr. Robert Kilvington, a practical and proficient botanist, who then had charge of the hothouses and garden. Mr. Kilvington formed a friendship with young Leidy and cheerfully instructed the boy who was so anxious to learn, and in later years took great pride in stating that he had been Leidy's botanical preceptor.
Early young Leidy displayed a gift for drawing and the high artistic skill which he acquired was exclusively due to self-cultivation. A small book of his portraits of shells dated February 1833, has been preserved, that shows his skill with a pencil in his tenth year. His school days ended with his sixteenth year. It was deemed expedient that he should now be taught some art by which to earn a livelihood and his father was anxious that Joseph should utilize his skill in drawing by becoming a sign painter, but young Leidy preferred employment with an apothecary where he applied himself so diligently that in a few months he was left in temporary charge of the retail business.
His loving stepmother cherished superior aspirations for all of her children, however, and hoped that they would choose professional careers and so she insisted that Joseph study medicine, for she fully believed that he would become a successful physician. Her constant endeavors finally won the rather reluctant consent of the father and in 1840 young Leidy became a pupil of Dr. James McClintock, then a private teacher of anatomy in College Avenue, where he devoted parts of 1840 and 1841 to practical anatomy. On October 26, 1841, Leidy matriculated at the University of Pennsylvania and was under the instruction of Dr. Paul B. Goddard, then demonstrator of anatomy in the University and Prof. Horner's prosector. Dr. Goddard was a skilful surgeon and devoted his leisure evenings in his office to microscopic studies and there young Leidy received his first lessons in the use of the microscope. Leidy attended three courses of lectures, submitted a thesis on "The comparative antomy of the eye of vertebrated animals," and complied with other requirements of that time whereupon the degree of Doctor of Medicine was conferred upon him by the University of Pennsylvania, April 4, 1844.
In the year after graduation, he was an assistant during six weeks in the laboratory of Robert Hare (q. v.), professor of chemistry, and then entered that of James B. Rogers (q. V.) lecturer on chemistry in the Medical Institute of Philadelphia, where he remained through the summer course. In the fall of 1844, he opened an office, No. 211 North Sixth Street, but found the restrictions on general practice so irksome that after two years' trial he turned to a university career as teacher.
In 1845 Leidy was appointed prosector under Dr. Horner (q. v.), professor of anatomy at the University of Pennsylvania and in 1846 was chosen demonstrator of anatomy in the Franklin Medical College where he served one session, then resigned to resume his position with Dr. Horner, in 1847, where he delivered to Horner's students a private course of lectures on human anatomy. While his kinsman. Dr. Napoleon B. Leidy, was coroner of the County of Philadelphia (1845–48), Dr. Joseph Leidy acted as coroner's physician and received fees for the autopsies he made. In April, 1848, Prof. Horner and Dr. Leidy visited England, Germany and France where they "visited hospitals and anatomical museums, and sought out eminent anatomists and surgeons," returning to Philadelphia in September. During this fall Leidy delivered a course of lectures on histology' and in the spring of 1849 he began a course on physiology in the Medical Institute of Philadelphia. His health failed, however, and he had to abandon this course.
In 1850 Dr. George G. Wood (q. v.), professor of the practice of medicine, desired to collect models, casts, preparations, etc., suitable for demonstration in future courses of instruction and he prevailed upon Leidy to accompany
