812 



SCIENCE 



[N. s. Vol. XXXVII. No. 961 



putes, SO little to his taste, he withdrew 

 from paleontological work altogether. 



Leidy was a student of facts, a lover of 

 positive knowledge. His attitude is indi- 

 cated by the following words from the 

 preface to his article on the extinct mam- 

 malia of Dakota (1869) : 



The present work is a record of facts. ... No 

 attempt has been made at generalizations or the- 

 ories which might attract the momentary attention 

 or admiration of the scientific community. 



Note the implied scorn of hasty specula- 

 tion, and remember that in 1869 most biol- 

 ogists had been carried off their feet by the 

 whirlwind of speculation which arose in 

 the wake of the Darwinian theory. Leidy 

 remained undisturbed, a firm devotee of 

 objective research. 



Leidy 's connection with the Philadelphia 

 Academy of Natural Sciences was long and 

 intimate. His earliest publication known 

 to me was a communication to the academy 

 in 1845. Two years later he became chair- 

 man of the board of curators; the collec- 

 tions of the academy long profited by his 

 devotion and wide knowledge of natural 

 history. From 1881 until his death he was 

 president. 



For nearly fifty years Leidy was a con- 

 stant attendant at the meetings of the 

 Philadelphia Academy and very often had 

 matters of interest to communicate, many 

 of which are briefly recorded in the Pro- 

 ceedings. Sixty years ago the meetings of 

 local scientific societies had an importance 

 and a charm, which have been miieh di- 

 minished by the developments of the last 

 twenty-five years. A generation ago there 

 were fewer specialists, and narrow inter- 

 ests did not dominate the majority of scien- 

 tific workers as much as to-day. When 

 naturalists met they spoke a common lan- 

 guage, and were mutually interested in 

 one another's discoveries — sixty years ago. 

 There were no national special societies. 



and no express trains to bring the mem- 

 bers together for three days, and to scatter 

 them asunder for three hundred and sixty- 

 two days — sixty years ago. The knowl- 

 edge of the individual was less intensive, 

 but his outlook was broader — sixty years 

 ago. To this old order — now passed for- 

 ever — Leidy belonged. The range of his 

 interests and of his contributions, as re- 

 vealed by a careful study of the Proceed- 

 ings of the Academy of Natural Sciences, 

 is astonishing, if viewed from the stand- 

 point of cotemporary specialization. There 

 are statements in his usually brief notes in 

 the Proceedings concerning regeneration in 

 Planarians, the formation of the cell wall 

 after the division of the cells, on the occur- 

 rence of internal parasitic plants in various 

 animals, on bacteria in the intestine of 

 toads, the sense of smell in snails, on a new 

 fossil, on the structure of cartilage, para- 

 sitic worms, sponges, Infusoria, Rotifera, 

 Annelids, extinct reptiles, fishes, parasitic 

 Hymenoptera — all incidental and in part 

 accidental observations, but reported with 

 unfailing accuracy. 



It should be recorded that time has 

 greatly emphasized the importance of some 

 of Leidy 's original discoveries, as of the 

 existence of a bacterial fiora in the intes- 

 tine (1849). Particularly noteworthy are 

 his experiments with cancer, made in 1851.^ 

 He transplanted small fragments of a hu- 

 man cancer under the skin of a frog and 

 found that they maintained themselves for 

 a long period. At the close of the com- 

 munication, the author says: 



The experiment not only proved the independent 

 vitality of the tissues, which was generally ad- 

 mitted, but also rendered it extremely probable 

 that cancer was inoculable, for, as in the experi- 

 ments, the cancerous fragments continued to live 

 when introduced into cold-blooded animals, they 



' Froceedhigs Acad. Nat. Sci., Philadelphia, V., 

 p. 212. 



