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



Thus the comparison of Filaria Medinensis with Urolabes pa- 

 lustris leads to the inference, at least, that the former is a Uro- 

 labcs modified ; that its young are not capable of maintaining 

 an independent existence long enough to become propagative 

 agents ; that the embryo of Filaria Medinensis must be intro- 

 duced into the human body from without ; that inference is in 

 favour of this taking place through the skin, and not by way of 

 the alimentary canal ; that this must take place when the worm 

 is in an embryo state, or after it has been liberated from the 

 egg; that, by the aid of the prehensile tail, and through the 

 narrowness of the body when very young, it might thus get into 

 a sudorific duct ; that, while there, it might be kept alive by the 

 moisture and the nutritive elements which the sudorific duct 

 contains ; and that, if provided with a sharp-pointed exsertile 

 oesophagus, like that of Urolabes palustris, it might from thence 

 bore its way into the subcutaneous cellular tissue ; while the 

 fact that the microscopic Filaridse do penetrate the bodies of 

 animals still further corroborates all these inferences. 



It is not my intention here to do more than allude to the 

 facts I brought forward formerly to support this argument, by 

 the coincidence of Urolabes pahstris occurring in great numbers 

 in a muddy pool of water in which the boys of a small school 

 bathed, accompanied by an extreme prevalence of Dracunculus 

 among them, and the almost total absence of Dracunculus in 

 another but very large school (in Bombay), in which the bathing 

 water is taken from a deep tank excavated in the trap-rock, 

 whose silty deposit presented no microscopic Filaridse of any 

 kind*, — because of itself it is inconclusive; but I may mention 

 with advantage, perhaps, prophylactically, that mud, Algse, and 

 freshwater plants harbour the microscopic Filaridse; and that 

 those tanks which, like the wells, are kept free from all these 

 accumulations do not contain any of them, for the simple reason 

 that such tanks afford them neither nidus nor nutriment. 



Impregnation. — If we infer that the embryo of Filaria Me- 

 dinensis is the young of one of the microscopic Filaridse, and 

 that it can only enter the body shortly after it is hatched, that 

 is, at the time when it does not much exceed the diameter 

 of the human blood-globule, its organs of generation are then 

 not developed, and it must therefore enter the body unimpreg- 

 nated. Again, it cannot be supposed to become impregnated 

 after getting into the tissues ; for, to infer this, we must assume 

 an amount of instinct and facility of communication, to enable 

 the male and female to come together under such circumstances, 

 as would be absurd; while we must also assume that all the 



* Trans. Med. and Phys. Soc. Bombay, No. 2, new series, p. 45, 1853-54. 



