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SCIENCE. 



[Vol. XVIII. No. 458 



new courses. It is safe to say that while he must already 

 he regarded as the most eminent meteorologist of our coun- 

 try, the true measure of his eminence will be better recog- 

 nized when those who follow the science that he enlarged 

 come to appreciate more fully what he did for it. 



W. M. D. 



PROFESSOR JOSEPH LEIDY: HIS LA.BORS IN THE 

 FIELD OF VERTEBRATE ANATOMY.' 

 We hear it said that at no time have the conditions for 

 intellectual attainment been so favorable as in the days of 

 Athenian supremacy. This may be true for communi- 

 "ties, but not for individuals. Surely the atmosphere of 

 Philadelphia from 1823 to 1891 favored greatness in science, 

 else there is no connection between the man and his environ- 

 ment. Is it not a truth that it only needs the man to come 

 forward to claim favoring conditions, to insist upon them as 

 Ms own, to have another like Joseph Leidy to he bred among 

 us ? A man to whom questions of birth and of patronage 

 were as nothing; one with a common school education and 

 without the subsequent advantages of training under distin- 

 guished masters; one to whom all things required for his 

 well-being appeared to come like the beneficent forces of 

 nature until we are apt to lose sight of the will and of the 

 steadfast purpose that directed them. He was never 



' ' limited and vexed 

 By a divided and delusive aim," 



but, fixed and invariable in his methods, he completed a 

 unique career. 



He dedicated himself early to anatomy, and it is about 

 this science as a central stem that all his labors cluster. 



Signs of immaturity are evident in the early labors of 

 most men. But this was not the case with Leidy. His first 

 paper, entitled, " Notes on the White Pond in New Jersey" 

 (Proc. Phil. Acad. Nat. Sci., 1847) exhibited the same clear 

 observation and lucidity of statement which characterize his 

 subsequent writings. The earliest of his anatomical papers 

 {" On the Fossil Horse of America," Proc. Phil. Acad. Nat. 

 Sci., 1847, 262) was in no respect inferior to any. of his nu- 

 merous records in the literature of paleontology of North 

 America. The word growth used in respect to him is inap- 

 propriate. In the best sense of the word he never grew. 

 Eather, like Bichat, he simply unfolded the native resources 

 which lay innate within him. 



For his graduating thesis in medicine he treated of the eye 

 in vertebrate animals. This essay has not been published. 

 In his twenty-second year, namely, July 29, 1845, he was 

 elected a member of the academy, and from this date to that 

 of his election to the cliair of anatomy in the University of 

 Pennsylvania, eight years later, his communications were 

 in the main devoted to the structure and properties of the 

 vertebrates. In this interval his industry was great, for he 

 was actively engaged at the same time in leaching, and in 

 assisting Professor W. E. Hoone in his anatomical work, and 

 Professor George B. Wood in dissecting and mounting path- 

 ological specimens. He described the retention of the inter- 

 maxillary suture in the skull of a New Hollander (Proc. 

 Phil. Acad. Nat. Sci., 1847), also one on the same bodies in 

 the boa constrictor resembling the Pacinian corpuscles 

 (Proc. Piiil. Acad. Nat. Sci., 1848, 27). He wrote a paper 

 on the existence of the intermaxillary bone in the embryo of 

 the human subject of the tenth week (Proc. Phil. Acad. Nat. 

 Sci., 1848, 45). 



1 Read at a special meetiDg of the Philadelphia Academy of Natural Sci- 

 ences, May 5, 1»91, by Harrison Allen, M.D. 



Remarkable instances of preservation of organized animal 

 matter were reported by him in 1847 (Proc. Phil. Acad. Nat. 

 Sci., 313) on the films and cartilaginous structures in the ex- 

 tinct genera Basilosaurus and Megalonyx, the former a 

 reptile of the rocene and the latter a mammal of the plio- 

 cene age. The vertebrae of Basilosaurus retained tissue 

 which when burnt gave out animal odor. Fibrous mem- 

 branes taken from one of the bones of Megalonyx exhibited 

 many of the characteristics of recent membrane; in the artic- 

 ular cartilages the corpuscles were well preserved and dis- 

 tinct. It was held that under favoring conditions the car- 

 tilaginous and fi^brous tissue might be preserved for an in- 

 definite period. 



In 1848 (Proc. Phil. Acad. Sci., 116) Dr. Leidy read re- 

 marks on the development of the Purkinjean corpuscles in 

 bone; on the intimate structure of articular cartilage, and on 

 the arrangement of aveolar sheath of muscular fascicule and 

 its relation to tendon. 



Cartilage was found to possess numbers of fine, transpar- 

 ent filaments, nearly uniform in thickness, having an aver- 

 age measurement of i^ lo^ of an inch. Hunter had claimed 

 this fibrilation, but without the aid of the microscope it can- 

 not be demonstrated. This cannot he said to be a prior 

 claim. Professor George A. Piersol has kindly informed me 

 that Dr. Leidy was the first to make the announcement of a 

 fact now accepted. KoUiler was inclined to regard the ap- 

 pearance as pathological. The fibrillar nature of the matrix 

 of all dense connective tissue, including cartilage and bone, 

 is now universally recognized. The comments upon the ar- 

 rangement of the aveolar sheath of muscular fascicute were 

 to the effect that " the filaments of fibrous tissue cross each 

 other diagonally around the muscular fascicute, forming a 

 double spiral extensive sheath. When the filaments reach 

 the rounded extremities of the fascicute they become straight 

 and in this manner conjoin with the tendinous filaments 

 originating at the extremities of the muscular fibres. The 

 importance of this arrangement can be readily understood, 

 from the diagonally crossing of the aveolar filaments, com- 

 paratively inelastic in themselves, the sheath is rendered 

 elastic, thus permitting the muscle fibres freely to move 

 without their action being interfered with." 



Dr. Leidy was in the habit of introducing these comments 

 in his lectures when speaking of the function of fibres de- 

 pending upon their position to each other rather than upon 

 differences in composition. 



In 1849 (Am. Journ. of the Med. Sci.) Dr. Leidy an- 

 nounced a plan of the construction of the liver. He as- 

 sumed that the follicul form of the liver in insects repre- 

 sented the plan of the primitive liver of the human embryo. 

 The subsequent changes which lead up to the complex sys- 

 tem of interlacing of tubules with their linings of biliary 

 cells was the result of the blind end of the follicle undergo- 

 ing subdivision by branching, each of the branches being 

 lined with the cells and the mouths of the now open tubules, 

 freely communicating with each other. This scheme was 

 the most philosophical of any hypothesis previously proposed 

 to account for the intricacy of the minute anatomy of the 

 liver; it was accepted at once by the scientific world, and is 

 itself an answer to the criticism sometimes made upon Dr. 

 Leidy's labors, that they are purely descriptive. The evolu- 

 tion of the system of glands appended to the alimentary ca- 

 nal was distinctly set forth by Leidy in this paper. Since 

 the relations of the liver as a blood-making and an excretory 

 organ have been better defined, other hypotheses than that 

 of Leidy have been proposed to elucidate its morphology. 



