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SCIENCE 



[N. S. Vol. LII. No. 1349 



the heterodox Cohnheim who taught that the 

 pus cell was merely an emigrated leukocyte, 

 he was not inclined to receive him as a worker 

 in his laboratory. One purpose of the visit 

 to Vienna was to study embryology under 

 Schenck, but the choice was not fortimate 

 and Schenck was soon forsaken. It is inter- 

 esting to note that Welch and Prudden found 

 themselves together in Vienna in their search 

 for an opportunity to study embryology. 



On the whole, the chief lure of Vienna for 

 the pathologist was its almost inexhaustible 

 store of pathological anatomical material. 

 The reign of Rokitansky was over, and his 

 successor was Heschl, the discoverer of the 

 methyl-violet reaction for amyloid, but a far 

 less significant personality. The greater at- 

 traction was the young Chiari, who was teach- 

 ing and working with the vigor which after- 

 wards became so notable and carried him by 

 way of Prague to Strassburg to succeed the 

 eminent von Recklinghausen. To him "Welch 

 went, but not to spend his entire time. There 

 survived in his mind, it appears, a residue of 

 distrust that pathology would after all afford 

 him a career in America, or was it the love 

 still for the more immediately practical as- 

 pects of medicine which led him to enter upon 

 courses on the skin under Hebra, on neurol- 

 ogy and psychiatry under Meynert, on the 

 eye and other special subjects? But Vienna 

 meant for Welch much more than gross 

 jpathology and the medical specialties. The 

 great city with its splendid museums of art, 

 its grand opera, and its vivid life introduced 

 features of another order into his experience, 

 feeding that general culture in literature, 

 history, and the fine arts which came to dis- 

 tinguish him quite as much as his many- 

 sided medical attainments. Welch remained 

 in Vienna until the Christmas holidays, when 

 he turned his steps for a second time toward 

 Strassbiu-g, spending a few days en route in 

 Wiirzburg with Rindfleiseh and his assistant 

 Ziegler. 



The second pilgrimage to Strassburg was 

 the carrying out of a plan formed by Welch 

 at the outset of his European study. He 

 recognized in von Recklinghausen the out- 



standing representative of the Virchow school 

 of pathologists, and his attendance upon the 

 autopsies at the Pathological Institute, while 

 he was a pupil of Waldeyer, had stimulated 

 his zeal to work directly under the master. 

 This desire could not be at once appeased, 

 for as we have seen, Welch lacked the prepa- 

 ration in normal histology which he regarded 

 as essential. But now that this requisite was 

 supplied and the work with Ludwig and with 

 Cohnheim had provided a fair foundation for 

 further building, Welch offered himself to 

 von Recklinghausen and was accepted. 



As another indication of the commotion 

 which Cohnheim's investigations were making 

 in the placid waters of Virehowian pathology, 

 it may be cited that once von Recklinghausen 

 learned Welch was fresh from the lalboratory 

 of that heretical pathologist, he chose as a 

 theme for his special study the inflammation 

 of the cornea of the frog induced by various 

 caustic chemicals. The essential point of dif- 

 ference involved in the contentions of the 

 Virchow and the Cohnheim schools related to 

 the origin of the pus cell. Was it derived by 

 multiplication from the fixed tissue cells, or 

 was it a leukocyte emigrated from the blood? 

 The controversy has long been setled in favor 

 of the latter, or Cohnheim view; but in Jan- 

 uary, 1878, and for many years thereafter it 

 raged with vigor and even bitterness. The 

 cornea was selected because of its condition of 

 non-vascularity. The novel experimental pro- 

 cedure employed at von Recklinghausen's sug- 

 gestion by Welch was the excision of the cor- 

 nea after the injury and immersion in the 

 aqueous hvunor of the frog or bullock, and 

 observation continued over long hours under 

 the microscope. That cells moved toward the 

 injured spot in the non-vascular specimen was 

 shown beyond peradventure and even that they 

 divided; what was simpler, therefore, than to 

 conclude that migration is not dependent on 

 the presence of the blood, and hence pus cells 

 are not translated leukocytes? This infer- 

 ence, however, was not drawn by Welch, who 

 recognized that the reasoning is fallacious. 

 The full explanation of the observed phenom- 

 ena waited on later studies and even on recent 



