Mr. H. J. Carter on Microscopic Filaridse. 105 



Hence the differences between Filaria Medinensis and C/ro- 

 lahes palustris do not appear to be real, but modifications of the 

 former to meet the circumstances under which its development 

 takes place ; and this appears still more evident when we com- 

 pare the young F. Medinensis with Urolabes ; for here the former, 

 although without the organs of generation, still has the elon- 

 gated straight tail and a fully- developed alimentary canal, — so 

 that it at once is so far a Urolabes. There are no papillae ob- 

 servable on the head at this period, neither is there a spear- 

 pointed extremity to the oesophagus ; but it must be remem- 

 bered that the characteristic features of the head and tail are 

 only developed with maturity in the microscopic Filaridse, and 

 when young, they are all more or less alike. The young F. Me- 

 dinensis has, however, perhaps a larger tail proportionally than 

 the young of Urolabes, and is corrugated transversely, while it 

 is as large as many specimens of the latter which have arrived 

 at maturity : hence comes the question, whether the young F, 

 Medinensis be not a monster form ? and then, whether it be ca- 

 pable of existing after it has left the parent ? — points which lead 

 to the consideration of the mode in which Filaria Medinensis is 

 propagated. 



Propagation. — The propagation of Filaria Medinensis involves 

 many questions : viz., is this effected by the young ones, or has 

 the worm an external origin ? and if the latter, under what form 

 is it introduced into the human body, and whether through the 

 skin or through the alimentary canal ? Lastly, is impregnation 

 necessary ? and, if so, where does this take place ? 



To arrive at some conclusion respecting the propagation of 

 Filaria Medinensis by its young ones, it was evident that the 

 first object should be to ascertain if the young were capable of 

 maintaining an independent existence; and for this purpose I 

 took some from a healthy full-grown individual, two or three 

 hours after extraction, when they were strong, active, and appa- 

 rently without impairment of vitality ; and having placed a few 

 (for it does not do to take many, on account of the numbers 

 which die soon rendering the water putrid), with some water, in 

 three small saucers, each of which contained a little fine clay at 

 the bottom (which, for fixation, had been allowed to dry there 

 previously), I set them aside for observation under a glass case, 

 close to the window of my room. Furthermore, in one of the 

 saucers were placed a few bits of Nostoc, which had been soaked 

 in water to gelatinize them ; to a second, a little bunch of Con- 

 ferva glomerata, about as large as an almond, was added ; and 

 the third saucer contained nothing but the clay. In this way 

 the water remained fresh in each saucer, while the Nostoc afibrded 

 a kind of nidus and nutriment, and the Conferva and the clay 



