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



As regards the origin of F. Medinensis from Urolabes palus- 

 tris, there can be no doubt (as the reader may satisfy himself by 

 the illustrations) that there is an intimate resemblance between 

 the two ; to which it may be added, that Urolabes palustris is by 

 far the most generally and numerously spread of all the free 

 microscopic Filaridse in the island of Bombay that have come 

 under my observation ; but then the transverse stria?, which are 

 so prominently marked in the young Guinea-worm, are alto- 

 gether absent in Urolabes palustris, while they are present in 

 some of the others that I have described. What the value of 

 this difference may be, I am unable to state ; and it is true that 

 in the adnlt F. Medinensis they are so faint that they can only 

 be seen under a tolerably high microscopic power, when they 

 appear to be the transverse fibres of the muscular, rather than 

 ruga? of the tegumentary coat, which they clearly are in the 

 young Guinea-worm ; so that, after all, this difference between 

 Urolabes pulustris and F. Medinensis may not be much. 



Thus the origin, which is the key to the history, of Dracun- 

 culus is still unknown, and therefore remains a subject for 

 future and interesting inquiry, but not more so than the still 

 further elucidation of the Filaridse generally, both free and 

 parasitic ; for when we consider that the former abound in spe- 

 cies, and are spread in myriads probably all over the world 

 where there is vegetable matter for them to feed upon, in salt 

 as well as in fresh water, in the sea and on the land, while the 

 latter inhabit all animals, perhaps, more or less, down to the 

 lowest worms, — that many of the former leave their habitat and 

 vegetable food for a temporary residence in animals, to live thus 

 on animal food, and that therefore the whole of the parasitic 

 forms may be originally derived from the free ones, — that they 

 not only enter animals, but live and dwell also in plants, as the 

 Paste- worm in the wheat, and Anguillulina Dipsaci in Dipsacus 

 Fullonum*, — that a variable plurality may be peculiarly parasitic 

 on each animal, especially among the higher orders, there being 

 fourteen jVcmatoidea, of which the Filaridse are a family, in man 

 alone, — that some of them enter the bodies of animals as embryos, 

 and when sufficiently stored with nutriment, leave their hosts 

 solely for the purpose of generation, — that others, asDracunculus, 

 appear to go into the body already impregnated, and remain 

 there until their whole progeny are ready for delivery before they 

 make their exit, — that the muscles, the innermost parts of the 

 body, the eye, the heart, and the blood itself, are sometimes their 

 abode, and that in many instances their presence is still unac- 

 counted for, — these worms, at first apparently insignificant, from 

 their simple thread-like form and scarcity, are seen to assume 



* Gervais et Van Beneden, ' Zoologie Medicale,' vol. ii. p. 101. 



