546 THE ANIMAL PARASITES OP MAN 



a long time under the skin of the connective tissue entirely latent. Only after 

 completing its full growth — the period of incubation appears to be from eight 

 to ten months — does it leave the papillary bodies of the corium by the forma- 

 tion of an abscess. 



The medina worm is most frequently found in tropical countries, particu- 

 larly in the Old World : in Arabia, around the Persian Gulf, upon the Ganges, 

 the Caspian Sea, in Upper Egypt, Abyssinia and Guinea. It has also been 

 carried to South America. 



The filaria embryos enclosed in the uterus can only secure their freedom 

 by rupture of the mother animal. How their further dissemination in the 

 human organism takes place has not yet been definitely determined. It has 

 been thought that the embryo finds ingress through the skin. Some authors 

 assume that infection is conveyed by drinking-water. Probably the worm 

 finds a hold around the lower extremities, especially about the malleoli. It is 

 much more rarely found upon the upper parts of the body. 



The symptoms resemble the formation of a furuncle, at the base of which 

 the parasite is seen. Upon extraction of the worm, rupture of the parasite 

 should be avoided, and care should be taken to leave no fragments behind, 

 for, otherwise, decided inflammation soon appears. 



A more delicate and smaller parasite is : 



Filaria loa Giiyot, 1778, 



which lodges between the conjunctiva and bulbus oculi, and gives rise to abscess 

 formation in this region. The parasite is found chiefly in negroes upon the 

 west coast of Africa, also in South America and in the Antilles. 



The other filariae are not of special interest. Among these I may mention 

 the filaria lentis, Diesing, 1851, the filaria hominis bronchialis, Eudolphi, 1819, 

 the filaria labialis, Pane, 1864, the filaria inermis, Grassi, 1887, the filaria 

 immitis, Leidy, 1856, the filaria reetiformis, Leidy, 1880, the filaria hominis 

 oris, Leidy, 1850, the strongylus subtilis. Loos, 1895, and the filaria volvulus, 

 Leuckart, 1893. 



Filaria Bancrofti, Cobbold, 1887. 



The embryos of this parasite were found in the fluid of a hydrocele by 

 Demarquay in 1863 in a Havanese. They were found later in the blood, 

 the urine, and in the chyle in so-called lymph-scrotum and in elephantiasis. 

 Bancroft and Lewis found the mature sexual forms in the lymph-vessels. The 

 females bear living young, which enter the blood with the lymph-stream. Ac- 

 cording to Manson they enter the blood only after sunset; after midnight 

 their number again decreases. If the patient sleep during the day, the em- 

 bryos appear in the blood during the daytime. 



This periodic appearance is explained by v. Linstow by the circumstance 

 that the peripheral cutaneous vessels dilate during sleep, and thereby permit 

 the entrance of the embryos, which otherwise would only be present in the 

 larger vessels. Manson states that the appearance of the embryos is simul- 

 =taneous with the swarming of mosquitoes, which suck the blood of the affected 

 •person, and are then filled with embryos. A part of the young brood develop 



