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XII. — Observations on the Structure and Nature of the Filaria medi- 

 nensis, or Guinea Worm. By George Busk, F.L.S., &c. 



(Read April 15, 1846). 



The subject of parasitic diseases, or the study of those morbid af- 

 fections of both animals and plants, which are caused by the attacks 

 of parasitic organisms of one or the other kingdom, is so intimately 

 connected with microscopic research, and depends for its ultimate, 

 complete elucidation so much upon the application of the microscope, 

 that the following observations relative to one of the most important 

 parasites of the human frame, may not, I hope, be considered altoge- 

 ther irrelevant to the objects of this Society. Having had many op- 

 portunities of observing instances of the occurrence of the Guinea 

 worm in this country, I have arrived at some conclusions with regard 

 to it, which, if found to be correct, will be of interest not only in 

 the particular instance of that worm, but may perhaps analogically 

 apply to a much greater extent among the nematoid Entozoa. The 

 subject, however, as it relates to the Filaria medinensis, cannot be 

 pursued to the full extent in this country, nor in Europe. It is re- 

 served for the observer in Africa or Asia to fill up the great gaps 

 which I believe yet exist in the complete history of this very trouble- 

 some Entozoon. 



As, from the rarity of the occurrence of the Guinea worm here, 

 lew, even among medical men, can be presumed to be very familiar 

 with what is already known regarding it, I may perhaps be excused, 

 before entering upon the proper subject of this paper as it concerns 

 microscopic research, for adverting very briefly to a few of the 

 main points connected with the natural history of the Entozoon; 

 and the more so, as all these facts in some degree tend to confirm 

 the conclusions at which I am disposed to arrive from considerations 

 drawn from its anatomical structure. 



The Filaria medinensis or Guinea worm is an extremely common 

 parasite of the human frame in those parts of the world where it is 

 endemic. Fortunately, however, these parts are neither numerous 

 nor very extensive. They are chiefly certain regions of tropical 

 Africa and Asia. The proper habitation of the worm is in the torrid 

 zone, but it is not confined to that zone, nor does it occur by any 

 means in all tropical countries. It is met with, according to Kiinse- 



