648 



NEMA ftiELMINTHES 



from the graceful curves of M. hancrofti. The anterior V-spot 

 can be seen, and probably opens at the apex to the exterior, as 

 Penel has observed that the stain penetrated easily at that spot; 

 probably there is also an opening at the tail-spot. In stained 

 specimens the first 8 is clear, without nuclei; at 62 /^the column 

 of nuclei is broken by an irregular transverse spot ; at 99 by a 

 triangular spot; at 253 ^ by a large and at 267 by a small spot. 

 The last nuclei are arranged in single file. One noticeable thing 

 about these embryos is the scarcity with which they are met with 

 in the peripheral blood as compared with those of F. hancrofti. 

 No explanation of this is forthcoming at present. 



It has been thought by Manson that the further stages of the 

 life-history will be found in a mango-fly (Chrysops dimidiatus), and 

 this has been shown to be the case by Leiper, who also finds a 

 development in C. silacea, but the method of infection of man is 

 unknown. 



After entering the human body, it would appear probable that 

 the v/orm takes some three to four years to reach sexual maturity, 

 and that it is long-lived — i.e., fifteen or more years. The reason for 

 believing this is the fact that immature forms may be noted in 

 children and the fully grown worm found in the adult. When the 

 worm dies, it may become cretified. 



Table showing the Differences between the Embryos of Filavia 

 bmcrofti and Loa loa. (Modified from Dr. G. C. Low.) 



Average length . . 

 Average breadth 



Break in cells from head 

 V-spot from head 

 Eggs (average) . . 



Character of curves in 

 dried specimens on 

 slides 



Periodicity 



Periodicity when habits 

 of sleeping and wak- 

 ing changed 



Filana hancfofti 

 Embryo 



0*3 1 7 millimetre 

 o-oo84-o*oo75 millime- 

 tre 



0-050 millimetre 

 0-090 millimetre 

 0-050 X 0-033 millime- 

 tre 



Spiral coils 



In blood at night (or 

 in equal numbers in 

 blood by day and 

 night, Fiji, etc.) 

 Inverted 



Loa loa Embryos. 



0-245 millimetre 

 0-0075-0-0070 millime- 

 tre 



0-042 millimetre 

 o-o6o millimetre 

 0-042 X 0-033 millime- 

 tre 



In wavy lines 



In blood by day 



No change 



Pathogenicity. — It may be noted under the skin of the finger, the 

 back, the breast, the scrotum and penis, the eyelid, under the 

 conjunctiva, the mucosa of the tongue. It moves quickly, and 



