1896.] NATURAL SCIENCES OF PHILADELPHIA. 273 



will probably continue to be the case until some Manson takes 

 residence in West Africa. 



The presence of Filaria embryos in the blood does not necessarily 

 give rise to disease, their transverse diameter (t^Vo inch) being as a 

 rule such as to enable them to traverse the narrowest channels of 

 the blood and lymph. Occasionally, however, they occlude these 

 vessels and this is due to the fact that the embryos are prematurely 

 born enclosed in a sac or sheath of globular form, the transverse 

 diameter of which is about 7^0 inch. Disease in man occasioned 

 by the Filaria is, therefore, the result of disease in the Filaria itself. 

 If the adult female Filaria produces the young in a physiological 

 manner they are innocuous to their host; if, through disease or 

 irritation, she brings them forth prematurely, they obstruct the lymph 

 channels and produce one or more of the diseases grouped under the 

 title of filariasis. According to Manson, " it is very certain that in 

 the great majority of instances in which the blood is infested with 

 Filariae, no harm whatever accrues.". 



The principal diseases to which the Filaria gives rise ai'e abscesses, 

 lymphangitis, dermatitis and cellulitis, erysipelas, orchitis, chyluria, 

 chylous dropsy of the peritoneum, chylous dropsy of the tunica 

 vaginalis, varicose groin glands, lymph scrotum and elephantiasis. 



The disease or rather the symptom that induced me to search for 

 the Filaria Avas chyluria, which is not a common manifestation of 

 filariasis even in the tropics. 



It is an interesting fact that the diseases to which the Filarise give 

 rise are entirely due to mechanical interference with the circulation 

 of lymph and blood ; no toxines, or at least none inimical to man 

 seem to be generated by this parasite and this fact is in marked 

 contrast to what is observed in the ordinary infectious diseases. In 

 the latter, as is well known, the products of bacterial activity are 

 intensely toxic. I would venture to suggest, in explanation of this 

 anomaly, that excretory products diminish in toxicity to man in 

 direct ratio with the ascent in the scale of being of the organism 

 that discharges them. 



The most remarkable fact in connection with the habits of Fi7ana 

 nodurna is that it is found in the suj^erficial capillaries solely 

 or chiefly during the evening and night. On several occasions I 

 have examined the blood of my patient at noon or thereabouts and 

 have found the parasites either absent altogether or very sparsely 

 present ; whereas at night they have always been abundant. This 



