Filaria ha 45 



evidence of his patient that such a swelhng may be rubbed to 

 remove it^ so that the evidence is at least somewhat confused. 



It can hardly be that the parasite in its migrations stimulates 

 nerve fibers or endings and thus produces as secondary results 

 the conditions ; for any excitation of sensory elements is inad- 

 missible, as the swellings are distinctly declared by most authors 

 to be painless. Hence Blanchard's suggestion of similarity to 

 the symptoms evoked by Hypodcnna lincata, a fly larva that 

 carries out subcutaneous migrations, hardly meets the conditions 

 of the case. Looss (1905) calls attention to a more striking 

 parallel between the Calabar swellings and those seen at times 

 in cases of Spargaiinni Maiisoiii, a migrating cestode larva which 

 occurs in the East. 



Hardly more acceptable as an explanation of Calabar swell- 

 ings is the view that the Loa in its movements stimulates unduly 

 reflex or sympathetic fibers. The infrequence of the swellings 

 and their distribution as compared with the nervous elements 

 speak distinctly against the supposed relation. 



Convinced of the insufiiciency of previous efiforts to explain 

 the tumefactions, Manson (1903) advanced the view that they 

 are caused by the discharge of embryos into the tissues. This 

 discharge of embryos from the parental form is intermittent, 

 and would produce the swellings by acting as a mild irritant and 

 causing a transient edema. In most respects this view meets the 

 conditions thoroughly, and it can hardly be said that definite 

 facts are recorded as yet which it fails to explain. Yet its 

 acceptance involves distinctly the concession that ^ not all cases 

 of infection with F. loa are subject to Calabar swellings; for 

 when the host harbors the male parasite alone, or also only 

 immature females, there can be no discharge of embryos into 

 the tissues and consequently no swellings produced. The theory 

 of Manson conforms to the facts in so far that cases of F. loa 

 are on record and are also distinctly noted by physicians (Zie- 

 mann. 1905) in the infected region in which Calabar swellings 

 do not occur. On the other hand, there are cases in which t1ie 

 swellings are found at such an early period after the comino- of 

 the. host into infected territorv that the Loa could not have 



