Physician contributions to nonmedical science: Joseph Leidy, parasitologist, paleontologist, microscopist W.E. SWINTON
If the year 1976 is mainly memorable for the United States, which is celebrating its bicentennial, it is equally memorable for the city of Philadelphia, which became the heart of the new republic. Thus the history of the growth of that city has more than local interest, and it provides a window through which we can see the development of thought, as well as civic conscience, and the background in which such notables as Benjamin Franklin and Drs. Wistar and Benjamin Rush performed their several works. Pennsylvania is named after William Penn, the English Quaker, but Penn had visited Germany and this encouraged the flow of German immigrants to the new state. Much of this was due to religious persecution in the Rhenish Palatinate, and among the many refugees was a John Jacob Leydig who arrived in Philadelphia in 1729 and settled on 200 hectares purchased from the Penns. The family had several scholars, theological or biological, in its lineage. John Jacob had a son of the same name, who became a potter of much distinction and a soldier in the revolution. He married Marie LeFebre, sister of a marshal of Napoleon I and a peer of France. These two, John Jacob Leydig and Marie, became the grandparents of Joseph Leidy, whose surname had been modified by English authority. John's father, Philip, was a successful hat manufacturer, who had married a German lady, and thus introduced further important genetic strains into the family of four. Joseph was the third of these, his mother dying only 20 months after his birth. Joseph was reared by a stepmother, whose prescience and careful training controlled the boy's education and determined his pathway to medicine. This encouragement, added to a possibly inherited artistic tendency, was to play a very important part in his life, for young Joseph was not a scholar by nature but a child who loved nature. He wandered off in search of flowers and insects, minerals and rocks, rather than take part in the games or organized activities of his schoolfellows. Here again one may question the acquisition of his great powers of observation. Were they in the genes? Or based on this early discovery of form and colour in nature? The "seeing-eye", to be made so much of by Thomas Carlyle, was clearly possessed by Leidy and was accom-
panied by skills in dissection and delineation. These were fundamental instruments in his pioneer studies in anatomy, protozoology, parasitology and vertebrate paleontology. Born Sept. 9, 1823, he entered unknowingly into a world of new freedom in the investigation of nature and its phenomena. He entered also into schools of original thought. Philadelphia had established the first American school of anatomy in 1762. This was a private venture of Dr. Shippen, and the practice rapidly grew, so that early in the 19th century Philadelphia was claiming to be as well equipped as Edinburgh in the field. It was to a private teacher of anatomy that the young man went before his entry into the University of Pennsylvania, where he graduated in medicine in 1844. His competence and interest in anatomical
tensive excavation and levelling. Bones were being discovered, in such quantity that occasionally they were used to build small cabins such as Bone Cabin, now a dinosaur locality of fame. Some bones were so large and intriguing that only anatomists could determine them. In Philadelphia Leidy was the recipient of as many of them as he could handle. He was asked to join an expedition to these lands of bones, but at the same time the professorship of anatomy became vacant. If he went to the bones, the chair might go to someone else; if he took the chair, the bones would surely come to him. He became professor of anatomy in 1853. He had become librarian and curator of the Academy of Sciences in 1846 and shortly afterward was made a trustee, and ultimately president, of the academy. The bones he identified were often later sent elsewhere but many remain in the academy, testimony to a man and age that was of great importance in the history of science. It is said that there were four main periods in his career: parasitologist until 1856, vertebrate paleontologist from 1850 or so until 1872, microscopist from 1872 to 1876, and parasitologist again after 1876. Among his earliest discoveries made from fossil remains was the ancestry detail are shown in the subject of his of the horse. ("On the Fossil Horse of MD thesis, "The Comparative Ana- America" 1947.) He showed that over tomy of the Eye of Vertebrated Ani- some 50 million years the horse had mals", and it is not surprising therefore developed from a dog-sized browser to that the appeal of general practice was the noble creature of the grasslands of so slight or, as it has been inferred, the great American plains. It then the response of Philadelphians to the became extinct in North America, but new practitioner was so delayed, that members of its family had escaped to by 1846 he abandoned the thought of Asia, and Columbus and his men and general practice for ever. the French discoverers of Canada were His subsequent professional life was among those who reintroduced it to the to be so very closely associated with old homeland. The Canadian Indians the Academy of Natural Sciences of looked on the "French moose" with Philadelphia that this institution looms astonishment and wondered at its lack largest in his life, but it was not all. of horns. He was a demonstrator in anatomy at the Franklin Medical College; he be- Instructive meal came an assistant to the professor of In 1848 he published the first real anatomy m the University of Pennsylvania and was long associated with study of the liver ("Researches into the that department. Comparative Anatomy of the Liver"). These appointments were not fortuit- Around this time, when he was eating ous, but they happened at an important his dinner, he discerned some spots in time. What are now the states of a piece of pork. From this the anatomColorado and Wyoming and other mid- ist, microscopist and parasitologist exwestern regions were being developed. tracted not only a spiral worm but the The coming of the railroads meant ex- life story of Trichina spiralis. It was to CMA JOURNAL/OCTOBER 23, 1976/VOL. 115 819
lead to long-time inspections of butchers' shops and fishmongers' slabs for this and other parasites that were welcomed by physicians and scientists but viewed unenthusiastically by the vendors. Before me as I write are the yellowed and dusty pages of "A Flora and Fauna Within Living Animals", accepted for publication in 1851 but published only in April 1853 "by the Smithsonian Institute of Washington City". It is devoted to the anatomy of parasites, "entozoa, ectozoa, and entophyla", and is illustrated by 10 beautiful plates drawn by the author. The work is of much importance. In the introduction, Leidy covers the formation of the earth and the origin of life, giving optimum temperatures for the latter. He says (and in 1851 it was hardly current thought): Living beings originate in a formless liquid matter. The first step in organization is the appearance of a solid particle. An aggregation of organic particles constitutes the spherical, vesicular, nucleolated, nucleated, organic cell, the type of the physical structure or organization of living beings. The phenomena which characterize the living being are: (1) Origin or birth; (2) Nutrition and assimilations; (3) Exuration [Exuro, I presumel; (4) Development and growth; (5) Reproduction; (6) Death. These, in the aggregate, constitute life. The range of temperature necessary for [?active] life is 350F-1350F. On page 11 of this work, he makes the prescient analysis: The primitive species of living beings which appeared upon earth and those which have been successively and periodically produced, must have been the result of pre-existing natural conditions, or the former alone originated in this manner, and the latter were the. result of their transmutation under the influence of varying exterior conditions, or all species in all times originated directly through supernatural agency.
Portrait of Joseph Leidy, In the Weliconie institute, London, England. over America for determination, and Leidy was the great vertebrate paleontologist of his country. Yet he found time for other things. His "Synopsis of Entozoa" described and named more than 100 new species. His "Elementary Treatise on Human Anatomy" (1861) became a standard work and is now recognized as a classic. The Civil War
His work was to be interrupted, as was the life of many others, by the This statement, written 8 years be- Civil War, in which he played his part fore the publication of "The Origin of as an army surgeon. No doubt he apSpecies" is worthy of analysis, though proached this also with his benign not in this article. manner and his seeing eye. It must be characteristic of the man that this dreadful time, with its tragic toll on The Hadrosaurus young lives, figures little in his 600 But larger things were at hand. The works. His view was that death and first American dinosaur skeleton was extinction are the inevitable conclusion extracted from Haddonfield, New Jer- of life of every kind, though there is sey, now a suburb of metropolitan no evidence that he applied this philoPhiladelphia, and was studied and sophically to the misdirected energies named Hadrosaurus by Leidy. mci- of war. After the war, and after 20 dentally, his assumption of a bipedal years of vertebrate paleontology, he pose, with kangaroo-like stance while returned to the microscope and soft feeding, for these herbivorous dinosaurs tissues. He wrote (somewhere about was correct as compared with the re- 1872), "Formerly every fossil bone constructions made in London by his found in the states came to me, for English counterpart, Richard Owen. nobody else cared to study such things. Bones were now arriving from all But now professors - and -, with 820 CMA JOURNAL/OCTOBER 23, 1976/VOL. 115
long purses, offer money for what used to come to me for nothing, and in that respect I cannot compete with them. So now, as I get nothing, I have gone back to my microscope and my rhizopods and make myself busy and happy with them." It can now be said that the dashes represent the two younger paleontologists, Othneil Charles Marsh of Yale University and Edward Drinker Cope of Philadelphia, whose rivalry became notorious as they competed for specimens and results. Just before this, he had climaxed his fossil studies with "On the Extinct Mammalia of Dakota and Nebraska" (1869), which was described by the great American paleontologist Henry Fairfield Osborn as "possibly the most important paleontological work produced in the United States", though later works from several modern scientists have undoubtedly surpassed it in breadth and depth. His newer studies were equally successful. In 1872 he was again writing on microscopic anatomy, and 10 years later he revised articles on "Parasites and diseases they produce" and "Venomous insects and reptiles", which appear in volumes of Holmes's "System of Surgery", and in 1885 he wrote a treatise on intestinal worms in William Pepper's "System of Practical Medicine" (Vol. II). This was the first comprehensive work on these parasites published in the US. Aside from all this, he was until 1891 head of the Academy of Sciences and also professor of anatomy at the University of Pennsylvania. This phenomenal observer, meticulous writer and great teacher, who is recognized by his peers as the founder of American parasitology and a great vertebrate paleontologist was a quiet, dignified, humble man. He grasped the theories of Darwin gladly, as indeed he had anticipated some of the conclusions. He was without jealousy, realizing, as Isaac Newton did, that "the great ocean of truth" will need many fishermen and that there will be work for all. Joseph Leidy died April 30, 1891, aged 67. He had been married for 27 years but there were no children, and the Joseph Leidy II, also a doctor and biologist of note, was his nephew, not his son. Today, the Academy of Sciences stands witness to his foresight and energy, and outside the building a statue to his memory confronts the busy Philadelphians on Logan Avenue. Let us hope that some remember him References wARD HB: The Founder of American parasitology. J Parasitology 10: 1, 1923 SWINTON WE: The Dinosaurs. London, Allen and Unwin. 1970 Encyclopaedia Britannica, 1975
If the year 1976 is mainly memorable for the United States, which is celebrating its bicentennial, it is equally memorable for the city of Philadelphia, which became the heart of the new republic. Thus the history of the growth of that city has more than local interest, and it provides a window through which we can see the development of thought, as well as civic conscience, and the background in which such notables as Benjamin Franklin and Drs. Wistar and Benjamin Rush performed their several works. Pennsylvania is named after William Penn, the English Quaker, but Penn had visited Germany and this encouraged the flow of German immigrants to the new state. Much of this was due to religious persecution in the Rhenish Palatinate, and among the many refugees was a John Jacob Leydig who arrived in Philadelphia in 1729 and settled on 200 hectares purchased from the Penns. The family had several scholars, theological or biological, in its lineage. John Jacob had a son of the same name, who became a potter of much distinction and a soldier in the revolution. He married Marie LeFebre, sister of a marshal of Napoleon I and a peer of France. These two, John Jacob Leydig and Marie, became the grandparents of Joseph Leidy, whose surname had been modified by English authority. John's father, Philip, was a successful hat manufacturer, who had married a German lady, and thus introduced further important genetic strains into the family of four. Joseph was the third of these, his mother dying only 20 months after his birth. Joseph was reared by a stepmother, whose prescience and careful training controlled the boy's education and determined his pathway to medicine. This encouragement, added to a possibly inherited artistic tendency, was to play a very important part in his life, for young Joseph was not a scholar by nature but a child who loved nature. He wandered off in search of flowers and insects, minerals and rocks, rather than take part in the games or organized activities of his schoolfellows. Here again one may question the acquisition of his great powers of observation. Were they in the genes? Or based on this early discovery of form and colour in nature? The "seeing-eye", to be made so much of by Thomas Carlyle, was clearly possessed by Leidy and was accom-
panied by skills in dissection and delineation. These were fundamental instruments in his pioneer studies in anatomy, protozoology, parasitology and vertebrate paleontology. Born Sept. 9, 1823, he entered unknowingly into a world of new freedom in the investigation of nature and its phenomena. He entered also into schools of original thought. Philadelphia had established the first American school of anatomy in 1762. This was a private venture of Dr. Shippen, and the practice rapidly grew, so that early in the 19th century Philadelphia was claiming to be as well equipped as Edinburgh in the field. It was to a private teacher of anatomy that the young man went before his entry into the University of Pennsylvania, where he graduated in medicine in 1844. His competence and interest in anatomical
tensive excavation and levelling. Bones were being discovered, in such quantity that occasionally they were used to build small cabins such as Bone Cabin, now a dinosaur locality of fame. Some bones were so large and intriguing that only anatomists could determine them. In Philadelphia Leidy was the recipient of as many of them as he could handle. He was asked to join an expedition to these lands of bones, but at the same time the professorship of anatomy became vacant. If he went to the bones, the chair might go to someone else; if he took the chair, the bones would surely come to him. He became professor of anatomy in 1853. He had become librarian and curator of the Academy of Sciences in 1846 and shortly afterward was made a trustee, and ultimately president, of the academy. The bones he identified were often later sent elsewhere but many remain in the academy, testimony to a man and age that was of great importance in the history of science. It is said that there were four main periods in his career: parasitologist until 1856, vertebrate paleontologist from 1850 or so until 1872, microscopist from 1872 to 1876, and parasitologist again after 1876. Among his earliest discoveries made from fossil remains was the ancestry detail are shown in the subject of his of the horse. ("On the Fossil Horse of MD thesis, "The Comparative Ana- America" 1947.) He showed that over tomy of the Eye of Vertebrated Ani- some 50 million years the horse had mals", and it is not surprising therefore developed from a dog-sized browser to that the appeal of general practice was the noble creature of the grasslands of so slight or, as it has been inferred, the great American plains. It then the response of Philadelphians to the became extinct in North America, but new practitioner was so delayed, that members of its family had escaped to by 1846 he abandoned the thought of Asia, and Columbus and his men and general practice for ever. the French discoverers of Canada were His subsequent professional life was among those who reintroduced it to the to be so very closely associated with old homeland. The Canadian Indians the Academy of Natural Sciences of looked on the "French moose" with Philadelphia that this institution looms astonishment and wondered at its lack largest in his life, but it was not all. of horns. He was a demonstrator in anatomy at the Franklin Medical College; he be- Instructive meal came an assistant to the professor of In 1848 he published the first real anatomy m the University of Pennsylvania and was long associated with study of the liver ("Researches into the that department. Comparative Anatomy of the Liver"). These appointments were not fortuit- Around this time, when he was eating ous, but they happened at an important his dinner, he discerned some spots in time. What are now the states of a piece of pork. From this the anatomColorado and Wyoming and other mid- ist, microscopist and parasitologist exwestern regions were being developed. tracted not only a spiral worm but the The coming of the railroads meant ex- life story of Trichina spiralis. It was to CMA JOURNAL/OCTOBER 23, 1976/VOL. 115 819
lead to long-time inspections of butchers' shops and fishmongers' slabs for this and other parasites that were welcomed by physicians and scientists but viewed unenthusiastically by the vendors. Before me as I write are the yellowed and dusty pages of "A Flora and Fauna Within Living Animals", accepted for publication in 1851 but published only in April 1853 "by the Smithsonian Institute of Washington City". It is devoted to the anatomy of parasites, "entozoa, ectozoa, and entophyla", and is illustrated by 10 beautiful plates drawn by the author. The work is of much importance. In the introduction, Leidy covers the formation of the earth and the origin of life, giving optimum temperatures for the latter. He says (and in 1851 it was hardly current thought): Living beings originate in a formless liquid matter. The first step in organization is the appearance of a solid particle. An aggregation of organic particles constitutes the spherical, vesicular, nucleolated, nucleated, organic cell, the type of the physical structure or organization of living beings. The phenomena which characterize the living being are: (1) Origin or birth; (2) Nutrition and assimilations; (3) Exuration [Exuro, I presumel; (4) Development and growth; (5) Reproduction; (6) Death. These, in the aggregate, constitute life. The range of temperature necessary for [?active] life is 350F-1350F. On page 11 of this work, he makes the prescient analysis: The primitive species of living beings which appeared upon earth and those which have been successively and periodically produced, must have been the result of pre-existing natural conditions, or the former alone originated in this manner, and the latter were the. result of their transmutation under the influence of varying exterior conditions, or all species in all times originated directly through supernatural agency.
Portrait of Joseph Leidy, In the Weliconie institute, London, England. over America for determination, and Leidy was the great vertebrate paleontologist of his country. Yet he found time for other things. His "Synopsis of Entozoa" described and named more than 100 new species. His "Elementary Treatise on Human Anatomy" (1861) became a standard work and is now recognized as a classic. The Civil War
His work was to be interrupted, as was the life of many others, by the This statement, written 8 years be- Civil War, in which he played his part fore the publication of "The Origin of as an army surgeon. No doubt he apSpecies" is worthy of analysis, though proached this also with his benign not in this article. manner and his seeing eye. It must be characteristic of the man that this dreadful time, with its tragic toll on The Hadrosaurus young lives, figures little in his 600 But larger things were at hand. The works. His view was that death and first American dinosaur skeleton was extinction are the inevitable conclusion extracted from Haddonfield, New Jer- of life of every kind, though there is sey, now a suburb of metropolitan no evidence that he applied this philoPhiladelphia, and was studied and sophically to the misdirected energies named Hadrosaurus by Leidy. mci- of war. After the war, and after 20 dentally, his assumption of a bipedal years of vertebrate paleontology, he pose, with kangaroo-like stance while returned to the microscope and soft feeding, for these herbivorous dinosaurs tissues. He wrote (somewhere about was correct as compared with the re- 1872), "Formerly every fossil bone constructions made in London by his found in the states came to me, for English counterpart, Richard Owen. nobody else cared to study such things. Bones were now arriving from all But now professors - and -, with 820 CMA JOURNAL/OCTOBER 23, 1976/VOL. 115
long purses, offer money for what used to come to me for nothing, and in that respect I cannot compete with them. So now, as I get nothing, I have gone back to my microscope and my rhizopods and make myself busy and happy with them." It can now be said that the dashes represent the two younger paleontologists, Othneil Charles Marsh of Yale University and Edward Drinker Cope of Philadelphia, whose rivalry became notorious as they competed for specimens and results. Just before this, he had climaxed his fossil studies with "On the Extinct Mammalia of Dakota and Nebraska" (1869), which was described by the great American paleontologist Henry Fairfield Osborn as "possibly the most important paleontological work produced in the United States", though later works from several modern scientists have undoubtedly surpassed it in breadth and depth. His newer studies were equally successful. In 1872 he was again writing on microscopic anatomy, and 10 years later he revised articles on "Parasites and diseases they produce" and "Venomous insects and reptiles", which appear in volumes of Holmes's "System of Surgery", and in 1885 he wrote a treatise on intestinal worms in William Pepper's "System of Practical Medicine" (Vol. II). This was the first comprehensive work on these parasites published in the US. Aside from all this, he was until 1891 head of the Academy of Sciences and also professor of anatomy at the University of Pennsylvania. This phenomenal observer, meticulous writer and great teacher, who is recognized by his peers as the founder of American parasitology and a great vertebrate paleontologist was a quiet, dignified, humble man. He grasped the theories of Darwin gladly, as indeed he had anticipated some of the conclusions. He was without jealousy, realizing, as Isaac Newton did, that "the great ocean of truth" will need many fishermen and that there will be work for all. Joseph Leidy died April 30, 1891, aged 67. He had been married for 27 years but there were no children, and the Joseph Leidy II, also a doctor and biologist of note, was his nephew, not his son. Today, the Academy of Sciences stands witness to his foresight and energy, and outside the building a statue to his memory confronts the busy Philadelphians on Logan Avenue. Let us hope that some remember him References wARD HB: The Founder of American parasitology. J Parasitology 10: 1, 1923 SWINTON WE: The Dinosaurs. London, Allen and Unwin. 1970 Encyclopaedia Britannica, 1975
