CENTURY'S PROGRESS IN SCIENTIFIC MEDICINE 



of this idea could only be appreciated in the light of 

 later knowledge ; but even at the time of its coming it 

 sufficed to give a great impetus to that new medical 

 knowledge, based on microscopical studies, which had 

 but recently been made accessible by the inventions 

 of the lens-makers. The new knowledge clarified one 

 very turbid medical pool, and pointed the way to the 

 clarification of many others. 



Almost at the same time that the Polish medical stu- 

 dent was demonstrating the itch mite in Paris, it 

 chanced, curiously enough, that another medical stu- 

 dent, this time an Englishman, made an analogous dis- 

 covery, of perhaps even greater importance. Indeed, 

 this English discovery in its initial stages slightly ante- 

 dated the other, for it was in 1833 that the student in 

 question, James Paget, interne in Saint Bartholomew's 

 Hospital, London, while dissecting the muscular tissues 

 of a human subject, found little specks of extraneous 

 matter, which, when taken to the professor of compara- 

 tive anatomy, Richard Owen, were ascertained, with the 

 aid of the microscope, to be the cocoon of a minute and 

 hitherto unknown insect. Owen named the insect Tri- 

 china spiralis. After the discovery was published, it 

 transpired that similar specks had been observed by 

 several earlier investigators, but no one had previously 

 suspected, or, at any rate, demonstrated their nature. 

 Nor was the full story of the trichina made out for a 

 long time after Owen's discovery. It was not till 1847 

 that the American anatomist Dr. Joseph Leidy found 

 the cysts of trichina in the tissues of pork ; and another 

 decade or so elapsed after that before German workers, 

 chief among whom were Leuckart, Virchow, and Zen- 

 ker, proved that the parasite gets into the human sys- 



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