THE BAHAMA ISLANDS 397 



axis of the worm. Under high power a very delicate transverse striation could 

 be detected throughout the entire length of the animal. The body seemed to be 

 composed chiefly of closely packed minute cells, enclosed in a transverse, 

 striated, musculo-cutaneous cylinder. 



By careful focusing it was found that the head end contained a six- 

 lobed prepuce, and while the parasite was alive a very thin fang could be de- 

 tected, which stood out from the extreme end, when this prepuce was inflated. 

 Thy Filarice belong to the class of worms called Nematodes, and are three or 

 four inches in length. The sexes live together, and frequently are very closely 

 packed about one another. The female Filaria is the larger, both in length and 

 thickness. The two uterine tubes occupy the longer diameter of her body and 

 are filled with ova at various stages of development. In both sexes the mouth 

 end is slightly tapered. The vagina opens not very far from the mouth and 

 the anus just in advance of the tip of its tail. The male worm is character- 

 ized by being much more slender, by its marked tendency to curl and its pecu- 

 liar, sharply incurved tail. 



Ordinarily these worms lie in the lymphatic vessels of the body, and are 

 productive of no especial symptoms with the exception, in the common variety, 

 of the embryonic Filarice appearing in the peripheral circulation at night. 

 Under certain conditions, however, elephantiasis arabum has been produced 

 by the plugging up of the lymphatic circulation. In cases of elephantiasis 

 the embryo Filarice are never found in the blood. The reason for this, appears 

 to be that the embryo of the Filarice, which are supple, slim, and actively moving 

 organisms, can readily pass through the small lymphatics and vessels, but in 

 case of injury to the adult female worm, in place of giving birth to these 

 embryos, aborts and lays the eggs, which are usually attached inside of her 

 body, and being oval bodies nearly five times the diameter of the embryo, they 

 are quite incapable of traversing the small lymphatics, and hence plug them 

 up. This stoppage not only prevents any embryos which may subsequently be 

 born from reaching the peripheral circulation, but also causes the affected part 

 to swell. This theory is substantiated by the cases of elephantiasis which 

 develop in countries where the Filaria is so commonly found in the blood after 

 injury. 



Eecently and chiefly through the work of Dr. Patrick Manson,' mosquitoes, 

 especially the species Culex fatigans and Anopheles nigerrimus, have been 

 shown to be an important intermediary host of the Filarin noctiirnn. If fed on 



-Tropical Diseases, pp. 555-556. 



