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SCIENCE 



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



^geneies whose actions are tlie immediate 

 excitants of those organic and cellular changes 

 .or lesions constituting the visible reactions of 

 the tissues to the injurious influences taking 

 place in the course of the phenomenal process 

 designated disease. This new direction of de- 

 velopment was highly sympathetic to Welch 

 who had been a spectator at Breslau, at the 

 jprologue to this swiftly moving drama, when 

 Koch visited Cohn and Oohnheim in order to 

 pxhibit his anthrax cultures. Welch desired 

 first-hand knowledge of and experience in the 

 new field, and as the Johns Hopkins Hospital 

 was still in process of construction, we find 

 jhim setting out again, in the summer of 1884, 

 for Germany. 



I The new goal was Koch in Berlin. But an 

 interview with him at the Reichsgesundheit- 

 $aint led Welch on Koch's advice to go to 

 Munich for the autumn to study under Fro- 

 benius in Bollinger's laboratory, preparatory 

 to work under the master at a later date. It 

 appears that Koch was soon to leave the 

 Gesundheitsamt to be established in the Hy- 

 gienic Institute under university auspices, 

 near the Alexanderplatz. Frobenius proved a 

 slavish teacher of Koch's technique, which he 

 communicated to his pupils along with such 

 comments as he had gleaned from conversa- 

 tions with Koch. Still, it was a beginning in 

 the new field and the relatively unfavorable 

 conditions led again, as once before at Leip- 

 zig, to connections of great future importance. 

 Here Welch made the acquaintance of Hans 

 Buchner and also of Escherich, Lehmann, !N"eu- 

 paann, Celli and others who had come to fol- 

 low the first course in bacteriology given in a 

 university. Especially with Celli, who had 

 already begun his studies of the malarial para- 

 site, he formed an intimate and enduring 

 friendship. Welch followed at this time Kitt's 

 demonstrations in animal pathology in the 

 veterinary school and worked in von Petten- 

 kofer's institute of hygiene with the master 

 himseK and his assistant, Eenk. All was grist 

 that came to Welch's mill for in after years 

 the former experience was to bear fruit in his 

 important studies on the swine diseases and 

 the close interest in Theobald Smith's work. 



^nd the latter to contribute to that compre- 

 Jiensive grasp of the subject of hygiene now 

 Jaeing embodied in the new school of public 

 health at Baltimore, his latest and highly re- 

 markable creation. 



Welch did not go at once from Munich to 

 Berlin but acting still under Koch's direction 

 went in January to Gottingen to work under 

 Fliigge, who was professor of hygiene and 

 puch closer to Koch and being advised by 

 him. This period was in every way advan- 

 tageous, as Eliigge was a far more inspiring 

 and systematic teacher than Frobenius, and 

 his influence proved lasting and valuable. 

 Here again he became acquainted with fellow 

 students gathered in Gottingen for the same 

 purpose, who afterwards became distinguished 

 bacteriologists, such as MacFadyen, Nicolaier 

 ^nd Wyssokowitch. 



; The final touch in Welch's preparation in 

 the new bacteriology was administered by 

 Koch — a vivid teacher — who himself con- 

 ducted the courses, which he had previously 

 organized for military doctors which had such 

 far-reaching consequences. Fortune again 

 threw Welch and Prudden together, for the 

 latter who had taken over the laboratory at 

 the College of Physicians and Surgeons estab- 

 lished by the Alumni Association, was now in 

 Berlin also seeking training in the new science 

 of bacteriology. The course, which was of a 

 few weeks' duration, consisted essentially in 

 the practise of isolating bacterial species by 

 means of Koch's solid culture technique or by 

 passage of them through the animal body, in 

 order to effect separation of virulent from other 

 varieties, and in the consideration of form, 

 staining reactions and physiological and path- 

 ogenic propensities. The climax of the course 

 was the study of the bacillus inducing Asiatic 

 cholera. At this period not a little apprehen- 

 sion existed that Europe might again be vis- 

 ited by that scourge. The disease had raged 

 in India and Egypt and the year before had 

 gained a foothold in Europe in certain Medi- 

 terranean ports — hence the desirability of 

 mobilizing a small army of trained bacteriol- 

 ogists to combat that plague should it threaten 

 in earnest. Koch himself was deeply im- 



