Mr. H. J. Carter on Microscopic Filaridse. 107 



distance of the parts from the legs and feet, in so much that it 

 is comparatively seldom seen above the hips, strongly tends to 

 the conclusion that it gets into the human body through the 

 skin of the lower extremities, and that it is not introduced 

 through the alimentary canal. 



Then, as regards the form under which it is introduced, that 

 cannot be in the shape of an ovum if it be not taken in by the 

 mouth, because the ovum has no means of attaching itself to the 

 surface of the body, and the embryo no means of becoming 

 hatched or existing there for more than a few moments if 

 hatched without water, even supposing that by chance it had 

 lodged on and become adherent to any part of the skin. Thus 

 we must infer that it enters the body in the form of an embryo 

 worm. 



Assuming, then, that this embryo, of whatever species of 

 Filaria it may be, had that prehensile power of the tail which is 

 not only manifested by the whole group of UrolabeSf but by the 

 young Guinea-worm itself, while the young of these microscopic 

 Filaridse, when hatched, are not wider in their transverse dia- 

 meter than a human blood-globule, and the mouths of the 

 sudorific ducts which stud the surface of the body in myriads 

 not only exceed this in size, but contain within them elements 

 of nutrition, it does not seem far-fetched to assume that, under 

 the form of a UrolabeSj at the period mentioned (that is, shortly 

 after having been hatched), the embryo of Filaria Medinensis 

 might find at least a recess in the human body into which it 

 might wriggle itself by means of its tail, and within which it 

 might be kept moist, obtain nourishment, and be perfectly 

 secure from falling out, until prepared to go further. Then, 

 assuming also that its oesophagus was furnished with a sharp 

 exsertile point like that of Urolabes palustris (fig. 11 d), it might, 

 from the sudorific duct, bore its way into the subcutaneous cel- 

 lular tissue, where the development of Filaria Medinensis for the 

 most part takes place, — or deeper still, and then by its elonga- 

 tion follow a most intricate and tortuous course, before its head 

 arrived at the surface for extrication. 



That the embryos of some of the Filaridse have the power of 

 penetrating into the bodies of animals, has been proved by Sie- 

 bold* and Lespesf — by the former in the larvae of Lepidoptera^ 

 and by the latter in Termites ; and I myself saw the one which 

 I have called Urolabes parasitica in variable plurality in the 

 peritoneal cavity of a Nais, viz. N. albida, which I found inha- 

 biting the very Glceocapsa which 1 had collected for the sake of 

 the microscopic Filaridse of all kinds which always abound in it. 



* Ann. (les Sc. nat. t. iv. p. 55, &c., 1855. 

 t Ann. of Nat. Hist. vol. xix. p. 388, 1857. 



