ARTHROPODA 573 



In eight to fourteen days the posterior portion of the abdomen of the para- 

 site swells to the size of a pea. It contains from 60 to 100 eggs. After depos- 

 iting the eggs the parasite dies. By incautious manipulation in its removal 

 or by other trauma which affect the toes and cause the abdomen of the para- 



FiG. 57. — Sarcopsylla Penetkans, Sand- Fig. 58. — Sahcopsylla Penetrans, Removed 

 FLEA, Prior to its Entrance Under the from a Wound of thu Nail. 



Nail of the Toe. 



site to rupture, the ova are liberated, and stubborn ulcers develop which, if 

 neglected, cause the loss of the toes. Wound infection not rarely complicates 

 the further course. The parasite should be removed by carefully lifting it 

 out with a dull forceps. 



FLY LARV^ (Maggots) 



Ply larvEe are occasionally observed as parasites in man. The mother ani- 

 mals belong to the family of oestrides or of the muscides, the actual flies. The 

 clinical picture produced by larvae is known as myiosis externa or interna s. 

 intestinalis. 



In Europe myiosis externa is mostly produced by the larva of the muscides, 

 more rarely by the larva of oestrides. For the latter the larva of the hypo- 

 derma bovis, de Geer, or hypoderma diana, Brauer, are responsible. In the 

 tropics the gadfly boil of man is due to the dermatobia noxialis, Brauer, or the 

 ochromyia anthropophaga. As soon as the eggs of these flies have been depos- 

 ited upon the skin, the larvs pour forth, bore into the skin, and in the course 

 of a few months cause the affection which is known as the " gadfly boil " of 

 cattle, of the stag and of the roe. In cattle larvse are taken up by the mouth 

 and finally find their way under the skin ; whether the same course is followed 

 in man has not yet been proven. Eecovery occurs spontaneously, by the 

 egress of the parasites, or by surgical opening and extraction of the larvgg 

 from the carbuncle-like cutaneous swelling. Krautner observed a dipteren 

 larva in an isolated location. He extracted a larva of the hypoderma bovis 

 from the anterior chamber of the eye. 



The occurrence of oestrus larvae in the digestive apparatus of man has not 



