LOA LOA 



647 



ing to the neck. The viscera are enclosed in a cyHndrical musculo- 

 cutaneous tube. The mouth is terminal, small, unarmed, and sur- 

 rounded by a powerful muscular cone ; the oesophagus is short, and 

 without a bulb; the intestine opens via the rectum at the anus, 

 near the posterior extremity. The excretory pore is 0-65 milli- 

 metre from the anterior end of the body. 



The genital apparatus consists of a tubular testis and vas deferens, 

 filled with spherical spermatozoa, which terminates in a vesicula 

 seminalis situate in the neighbourhood of the bases of the spicules. 



The female is larger and thicker than the male, measuring in 

 the fresh condition 44 to 63 millimetres (may be from 32 to 57 milli- 

 metres in different conditions of preservation) in length, and from 

 0-38 to 0'49 millimetre in thickness. The cuticle and anterior 

 extremity resemble those of the male. 



The genital system consists of a vulva situated on a little eleva- 

 tion 23 in height, and distant some 2-5 millimetres from the 

 anterior .^extremity. This vulva leads into a thick-walled canal— 

 the vagina — -from which the two uterine tubes full of embryos and 

 eggs^diverge, and end in the ovaries. 



Life-History,— The life-history, unfortunately, is not well known. 

 The unsegmented egg, starting in the uterus with a length of 32 /j, 

 and a breadth of 17 ^, grows into 40 by 25 fj, in the morula stage, 

 and 50 by 25 jbb in the stage when a twisted and roUed-up embryo 

 can be seen. It now approaches the vulva, and the embryo unrolls 

 and elongates itself inside the egg membrane, which is now con- 

 siderably lengthened, measuring 250 to 260 /li in length by 5-5 to 

 6-6 ^ in breadth. The embryo now escapes from the mother, and 

 passes via the lymph-stream into the blood, where it is known as 

 Microfilaria diurna, and is noticed to have increased somewhat in 

 size, which Penel considers is due to imbibition of fluid by osmosis, 

 and now measures 298 by 7-5 ^. It will be noted, however, that 

 it does not quite fill up its sheath, which is generally empty in front 

 and behind for a short space. These embryos are only to be found 

 in the peripheral blood during the day, and not at night, but they 

 have no relation to sleep in the host like M. hancrofti, as they 

 are unaffected by altering the habits of the host, and making him 

 sleep in the day and work at night. When examined under the 

 microscope, they can be seen in irregular curves, which are different 



Fig. 277. — Embryo of Loa loa Guyot. 



