222 



PARASITES OF MAN 



caecal or terminal portion of the intestine to be partially reflected 

 upon itself. In regard to the circular 

 opening which Robin and myself de- 

 scribed as the anus, Bastian says there 

 is a rounded body, " about ^' in dia- 

 meter, with a dark or light spot in the 

 centre, according to the varying focal 

 distance, and which seems to represent 

 a central aperture. Sometimes, above 

 this, traces of two or three large cells 

 may be recognised, whilst behind no- 

 thing definite can be made out, save that 

 the cavity of the body is visible for 

 about jig" '. In other specimens of the 

 young worm the central body and spot 

 are wanting, but, in its stead, two lateral 

 sacculi are met with, about ~" i n dia- 

 meter, that communicate with the ex- 

 terior by a minute channel through the 

 integuments, which can sometimes be 

 distinctly recognised. At other times 

 the channel is obscured by protrusion, 

 which appears to have taken place 

 through it, of a minute bilobed papilla, 

 projecting Y^UUS" from the side of the 

 body. When the projections are seen, 

 the sacculi are indistinct." 



As Bastian found the young in all 

 stages of development from the germ 

 condition ^ 5 " in diameter up to the per- 

 fect embrvo.and as, moreover, he. like the 



Fio. 44. Embryos of Dracunculus. J ' 



Magnified 600 diameters. After rest of US, COuld detect no SCXUal Orifice 



in the adult Dracunculus, he was led to 



express his belief that the young were produced agamo-geneti- 

 cally. He went so far as to call the germs pseudova. It was with 

 great reluctance that I dissented from the views of so gifted an 

 observer as Bastian ; nevertheless, later researches have shown 

 that I was justified in not hastily concurring in the theory of a 

 non-sexual mode of reproduction for Dracunculus. 



Among the many advances of modern helminthology, the 

 discovery of the true source of the guinea- worm is not the least 

 important. To the late M. Fedschenko (the lamented and 



