THE GUINEA WORM 315 



terior part of the body by reason of being almost as wide as the parent worm. They 

 usually live deep in the mucosa and the embryos emerge from the ova laid in the 

 mucosa. The embryos escape from the eggs while still in the intestine, so that in 

 the faeces we only find actively motile embryos. The eggs, which are strung out 

 in a chain, never appear in the fasces except during purgation. As they greatly 

 resemble hookworm eggs, this is a point of great practical importance. In fresh 

 faeces we find hookworm eggs and Strongyloides embryos. The embryos are rather 

 common in stools in the tropics. These embryos have pointed tails and are about 

 250 X i3M- They have a double cesophageal bulb. They are about 250*1 when they 

 first emerge but may grow until they will approximate 500/1 in the fseces. If the 

 temperature is low, these rhabditiform embryos develop into filariform embryos, 

 which being ingested form the infecting stage. It has been demonstrated that 

 infection of man may also take place through the skin. If the temperature is warm, 

 2 5 to 35C., these embryos develop into: 



2. The free living form, Anguillula stercoralis. In this we have males and females, 

 with double cesophageal bulbs, the male about ^ inch (% mm.) long with an in- 

 curved tail and two spicules and the female about % 5 inch (i mm.) long with an 

 attenuated tail; these copulate and we have produced rhabditiform larvae, which 

 later change to filariform ones. At this time the length is about 550 microns. 

 These, being ingested, start up the parasitical generation. If these do not reach the 

 intestine they die out. 



FILARIID.E 



This family is of the greatest importance to man. It is also one 

 about which much confusion exists as to the adult type; hence anyone 

 finding adult filariae should fix them in hot 5% glycerine alcohol 

 (alcohol 70%), and subsequently mount in glycerine gelatin. Formalin 

 is not to be used, other than for a very brief period (two to six hours) 

 and then followed by the lacto-phenol method. 



These worms are most likely to be seen as writhing thread-like worms, especially 

 in the lymphatic glands and connective tissue, and about body cavities. They have 

 a lipped or simple mouth and a filariform oesophagus. The male has an incurved 

 tail with preanal and postanal papillae which may be even corkscrew-like as in F. 

 immitis. The spicules are unequal or there may be but one. The female is ovovivi- 

 parous, the vulva is at the anterior end and the uterus usually double. 



Dracunculus medinensis (Filaria medinensis). The Guinea or 

 Medina worm, of which until recently only the female was known, is 

 of great importance in parts of India, Africa, and Arabia. The female 

 is a thread-like worm, about 20 to 30 inches long. The habitat is the 

 subcutaneous and intermuscular connective tissue, especially of the 

 lower extremity. It develops without symptoms. Finally a blister- 

 like area appears on the surface of the leg, particularly about ankle- 

 joint, which soon forms a painful ulcer. From this opening the 



